diff --git a/src/graph/executor/StorageAccessExecutor.cpp b/src/graph/executor/StorageAccessExecutor.cpp
index 48fcdb58d3f..86b100a6076 100644
--- a/src/graph/executor/StorageAccessExecutor.cpp
+++ b/src/graph/executor/StorageAccessExecutor.cpp
@@ -37,11 +37,12 @@ struct Vid<std::string> {
 };
 
 template <typename VidType>
-DataSet buildRequestDataSet(const SpaceInfo &space,
-                            QueryExpressionContext &exprCtx,
-                            Iterator *iter,
-                            Expression *expr,
-                            bool dedup) {
+StatusOr<DataSet> buildRequestDataSet(const SpaceInfo &space,
+                                      QueryExpressionContext &exprCtx,
+                                      Iterator *iter,
+                                      Expression *expr,
+                                      bool dedup,
+                                      bool isCypher) {
   DCHECK(iter && expr) << "iter=" << iter << ", expr=" << expr;
   nebula::DataSet vertices({kVid});
   auto s = iter->size();
@@ -54,11 +55,19 @@ DataSet buildRequestDataSet(const SpaceInfo &space,
 
   for (; iter->valid(); iter->next()) {
     auto vid = expr->eval(exprCtx(iter));
-    if (!SchemaUtil::isValidVid(vid, vidType)) {
-      LOG(WARNING) << "Mismatched vid type: " << vid.type()
-                   << ", space vid type: " << SchemaUtil::typeToString(vidType);
+    if (vid.empty()) {
       continue;
     }
+    if (!SchemaUtil::isValidVid(vid, vidType)) {
+      if (isCypher) {
+        continue;
+      }
+      std::stringstream ss;
+      ss << "`" << vid.toString() << "', the srcs should be type of "
+         << apache::thrift::util::enumNameSafe(vidType.get_type()) << ", but was`" << vid.type()
+         << "'";
+      return Status::Error(ss.str());
+    }
     if (dedup && !uniqueSet.emplace(Vid<VidType>::value(vid)).second) {
       continue;
     }
@@ -73,16 +82,17 @@ bool StorageAccessExecutor::isIntVidType(const SpaceInfo &space) const {
   return (*space.spaceDesc.vid_type_ref()).type == nebula::cpp2::PropertyType::INT64;
 }
 
-DataSet StorageAccessExecutor::buildRequestDataSetByVidType(Iterator *iter,
-                                                            Expression *expr,
-                                                            bool dedup) {
+StatusOr<DataSet> StorageAccessExecutor::buildRequestDataSetByVidType(Iterator *iter,
+                                                                      Expression *expr,
+                                                                      bool dedup,
+                                                                      bool isCypher) {
   const auto &space = qctx()->rctx()->session()->space();
   QueryExpressionContext exprCtx(qctx()->ectx());
 
   if (isIntVidType(space)) {
-    return internal::buildRequestDataSet<int64_t>(space, exprCtx, iter, expr, dedup);
+    return internal::buildRequestDataSet<int64_t>(space, exprCtx, iter, expr, dedup, isCypher);
   }
-  return internal::buildRequestDataSet<std::string>(space, exprCtx, iter, expr, dedup);
+  return internal::buildRequestDataSet<std::string>(space, exprCtx, iter, expr, dedup, isCypher);
 }
 
 std::string StorageAccessExecutor::getStorageDetail(
diff --git a/src/graph/executor/StorageAccessExecutor.h b/src/graph/executor/StorageAccessExecutor.h
index 0978ca5bba3..0e18c9333bb 100644
--- a/src/graph/executor/StorageAccessExecutor.h
+++ b/src/graph/executor/StorageAccessExecutor.h
@@ -158,7 +158,10 @@ class StorageAccessExecutor : public Executor {
 
   bool isIntVidType(const SpaceInfo &space) const;
 
-  DataSet buildRequestDataSetByVidType(Iterator *iter, Expression *expr, bool dedup);
+  StatusOr<DataSet> buildRequestDataSetByVidType(Iterator *iter,
+                                                 Expression *expr,
+                                                 bool dedup,
+                                                 bool isCypher = false);
 };
 
 }  // namespace graph
diff --git a/src/graph/executor/query/AppendVerticesExecutor.cpp b/src/graph/executor/query/AppendVerticesExecutor.cpp
index d64a470cbe8..509e5cb4c2a 100644
--- a/src/graph/executor/query/AppendVerticesExecutor.cpp
+++ b/src/graph/executor/query/AppendVerticesExecutor.cpp
@@ -16,12 +16,12 @@ folly::Future<Status> AppendVerticesExecutor::execute() {
   return appendVertices();
 }
 
-DataSet AppendVerticesExecutor::buildRequestDataSet(const AppendVertices *av) {
+StatusOr<DataSet> AppendVerticesExecutor::buildRequestDataSet(const AppendVertices *av) {
   if (av == nullptr) {
     return nebula::DataSet({kVid});
   }
   auto valueIter = ectx_->getResult(av->inputVar()).iter();
-  return buildRequestDataSetByVidType(valueIter.get(), av->src(), av->dedup());
+  return buildRequestDataSetByVidType(valueIter.get(), av->src(), av->dedup(), true);
 }
 
 folly::Future<Status> AppendVerticesExecutor::appendVertices() {
@@ -30,7 +30,9 @@ folly::Future<Status> AppendVerticesExecutor::appendVertices() {
   auto *av = asNode<AppendVertices>(node());
   StorageClient *storageClient = qctx()->getStorageClient();
 
-  DataSet vertices = buildRequestDataSet(av);
+  auto res = buildRequestDataSet(av);
+  NG_RETURN_IF_ERROR(res);
+  auto vertices = std::move(res).value();
   if (vertices.rows.empty()) {
     return finish(ResultBuilder().value(Value(DataSet(av->colNames()))).build());
   }
diff --git a/src/graph/executor/query/AppendVerticesExecutor.h b/src/graph/executor/query/AppendVerticesExecutor.h
index bbe3d697d54..7138fdb6a08 100644
--- a/src/graph/executor/query/AppendVerticesExecutor.h
+++ b/src/graph/executor/query/AppendVerticesExecutor.h
@@ -22,7 +22,7 @@ class AppendVerticesExecutor final : public GetPropExecutor {
   folly::Future<Status> execute() override;
 
  private:
-  DataSet buildRequestDataSet(const AppendVertices *gv);
+  StatusOr<DataSet> buildRequestDataSet(const AppendVertices *gv);
 
   folly::Future<Status> appendVertices();
 
diff --git a/src/graph/executor/query/GetEdgesExecutor.cpp b/src/graph/executor/query/GetEdgesExecutor.cpp
index a129df1d3d2..8e248df8b9b 100644
--- a/src/graph/executor/query/GetEdgesExecutor.cpp
+++ b/src/graph/executor/query/GetEdgesExecutor.cpp
@@ -5,6 +5,7 @@
 #include "graph/executor/query/GetEdgesExecutor.h"
 
 #include "graph/planner/plan/Query.h"
+#include "graph/util/SchemaUtil.h"
 
 using nebula::storage::StorageClient;
 using nebula::storage::StorageRpcResponse;
@@ -17,7 +18,7 @@ folly::Future<Status> GetEdgesExecutor::execute() {
   return getEdges();
 }
 
-DataSet GetEdgesExecutor::buildRequestDataSet(const GetEdges *ge) {
+StatusOr<DataSet> GetEdgesExecutor::buildRequestDataSet(const GetEdges *ge) {
   auto valueIter = ectx_->getResult(ge->inputVar()).iter();
   QueryExpressionContext exprCtx(qctx()->ectx());
 
@@ -25,11 +26,28 @@ DataSet GetEdgesExecutor::buildRequestDataSet(const GetEdges *ge) {
   edges.rows.reserve(valueIter->size());
   std::unordered_set<std::tuple<Value, Value, Value, Value>> uniqueEdges;
   uniqueEdges.reserve(valueIter->size());
+
+  const auto &space = qctx()->rctx()->session()->space();
+  const auto &vidType = *(space.spaceDesc.vid_type_ref());
   for (; valueIter->valid(); valueIter->next()) {
     auto type = ge->type()->eval(exprCtx(valueIter.get()));
     auto src = ge->src()->eval(exprCtx(valueIter.get()));
     auto dst = ge->dst()->eval(exprCtx(valueIter.get()));
     auto rank = ge->ranking()->eval(exprCtx(valueIter.get()));
+    if (!SchemaUtil::isValidVid(src, vidType)) {
+      std::stringstream ss;
+      ss << "`" << src.toString() << "', the src should be type of "
+         << apache::thrift::util::enumNameSafe(vidType.get_type()) << ", but was`" << src.type()
+         << "'";
+      return Status::Error(ss.str());
+    }
+    if (!SchemaUtil::isValidVid(dst, vidType)) {
+      std::stringstream ss;
+      ss << "`" << dst.toString() << "', the dst should be type of "
+         << apache::thrift::util::enumNameSafe(vidType.get_type()) << ", but was`" << dst.type()
+         << "'";
+      return Status::Error(ss.str());
+    }
     type = type < 0 ? -type : type;
     auto edgeKey = std::make_tuple(src, type, rank, dst);
     if (ge->dedup() && !uniqueEdges.emplace(std::move(edgeKey)).second) {
@@ -52,7 +70,9 @@ folly::Future<Status> GetEdgesExecutor::getEdges() {
     return Status::Error("ptr is nullptr");
   }
 
-  auto edges = buildRequestDataSet(ge);
+  auto res = buildRequestDataSet(ge);
+  NG_RETURN_IF_ERROR(res);
+  auto edges = std::move(res).value();
 
   if (edges.rows.empty()) {
     // TODO: add test for empty input.
diff --git a/src/graph/executor/query/GetEdgesExecutor.h b/src/graph/executor/query/GetEdgesExecutor.h
index 39802c21f43..20446d87d23 100644
--- a/src/graph/executor/query/GetEdgesExecutor.h
+++ b/src/graph/executor/query/GetEdgesExecutor.h
@@ -19,7 +19,7 @@ class GetEdgesExecutor final : public GetPropExecutor {
   folly::Future<Status> execute() override;
 
  private:
-  DataSet buildRequestDataSet(const GetEdges *ge);
+  StatusOr<DataSet> buildRequestDataSet(const GetEdges *ge);
 
   folly::Future<Status> getEdges();
 };
diff --git a/src/graph/executor/query/GetNeighborsExecutor.cpp b/src/graph/executor/query/GetNeighborsExecutor.cpp
index 9c90e66c578..3737f741088 100644
--- a/src/graph/executor/query/GetNeighborsExecutor.cpp
+++ b/src/graph/executor/query/GetNeighborsExecutor.cpp
@@ -13,7 +13,7 @@ using nebula::storage::cpp2::GetNeighborsResponse;
 namespace nebula {
 namespace graph {
 
-DataSet GetNeighborsExecutor::buildRequestDataSet() {
+StatusOr<DataSet> GetNeighborsExecutor::buildRequestDataSet() {
   SCOPED_TIMER(&execTime_);
   auto inputVar = gn_->inputVar();
   auto iter = ectx_->getResult(inputVar).iter();
@@ -21,7 +21,9 @@ DataSet GetNeighborsExecutor::buildRequestDataSet() {
 }
 
 folly::Future<Status> GetNeighborsExecutor::execute() {
-  DataSet reqDs = buildRequestDataSet();
+  auto res = buildRequestDataSet();
+  NG_RETURN_IF_ERROR(res);
+  auto reqDs = std::move(res).value();
   if (reqDs.rows.empty()) {
     List emptyResult;
     return finish(ResultBuilder()
diff --git a/src/graph/executor/query/GetNeighborsExecutor.h b/src/graph/executor/query/GetNeighborsExecutor.h
index e7d79786e59..7ba20c19cf5 100644
--- a/src/graph/executor/query/GetNeighborsExecutor.h
+++ b/src/graph/executor/query/GetNeighborsExecutor.h
@@ -21,7 +21,7 @@ class GetNeighborsExecutor final : public StorageAccessExecutor {
 
   folly::Future<Status> execute() override;
 
-  DataSet buildRequestDataSet();
+  StatusOr<DataSet> buildRequestDataSet();
 
  private:
   using RpcResponse = storage::StorageRpcResponse<storage::cpp2::GetNeighborsResponse>;
diff --git a/src/graph/executor/query/GetVerticesExecutor.cpp b/src/graph/executor/query/GetVerticesExecutor.cpp
index 6a71c737e67..20014b74090 100644
--- a/src/graph/executor/query/GetVerticesExecutor.cpp
+++ b/src/graph/executor/query/GetVerticesExecutor.cpp
@@ -21,7 +21,9 @@ folly::Future<Status> GetVerticesExecutor::getVertices() {
   auto *gv = asNode<GetVertices>(node());
   StorageClient *storageClient = qctx()->getStorageClient();
 
-  DataSet vertices = buildRequestDataSet(gv);
+  auto res = buildRequestDataSet(gv);
+  NG_RETURN_IF_ERROR(res);
+  auto vertices = std::move(res).value();
   if (vertices.rows.empty()) {
     // TODO: add test for empty input.
     return finish(
@@ -55,7 +57,7 @@ folly::Future<Status> GetVerticesExecutor::getVertices() {
       });
 }
 
-DataSet GetVerticesExecutor::buildRequestDataSet(const GetVertices *gv) {
+StatusOr<DataSet> GetVerticesExecutor::buildRequestDataSet(const GetVertices *gv) {
   if (gv == nullptr) {
     return nebula::DataSet({kVid});
   }
diff --git a/src/graph/executor/query/GetVerticesExecutor.h b/src/graph/executor/query/GetVerticesExecutor.h
index 24d2c249039..d52ff39adb8 100644
--- a/src/graph/executor/query/GetVerticesExecutor.h
+++ b/src/graph/executor/query/GetVerticesExecutor.h
@@ -19,7 +19,7 @@ class GetVerticesExecutor final : public GetPropExecutor {
   folly::Future<Status> execute() override;
 
  private:
-  DataSet buildRequestDataSet(const GetVertices *gv);
+  StatusOr<DataSet> buildRequestDataSet(const GetVertices *gv);
 
   folly::Future<Status> getVertices();
 };
diff --git a/src/graph/executor/query/UnwindExecutor.cpp b/src/graph/executor/query/UnwindExecutor.cpp
index de1d774e0a7..1e42993fa3b 100644
--- a/src/graph/executor/query/UnwindExecutor.cpp
+++ b/src/graph/executor/query/UnwindExecutor.cpp
@@ -26,7 +26,7 @@ folly::Future<Status> UnwindExecutor::execute() {
     std::vector<Value> vals = extractList(list);
     for (auto &v : vals) {
       Row row;
-      if (!emptyInput) {
+      if (!unwind->fromPipe() && !emptyInput) {
         row = *(iter->row());
       }
       row.values.emplace_back(std::move(v));
diff --git a/src/graph/executor/test/GetNeighborsTest.cpp b/src/graph/executor/test/GetNeighborsTest.cpp
index 9edf1352e05..55c3ba5e48c 100644
--- a/src/graph/executor/test/GetNeighborsTest.cpp
+++ b/src/graph/executor/test/GetNeighborsTest.cpp
@@ -69,7 +69,8 @@ TEST_F(GetNeighborsTest, BuildRequestDataSet) {
   gn->setInputVar("input_gn");
 
   auto gnExe = std::make_unique<GetNeighborsExecutor>(gn, qctx_.get());
-  auto reqDs = gnExe->buildRequestDataSet();
+  auto res = gnExe->buildRequestDataSet();
+  auto reqDs = std::move(res).value();
 
   DataSet expected;
   expected.colNames = {kVid};
diff --git a/src/graph/planner/plan/Query.cpp b/src/graph/planner/plan/Query.cpp
index aa1c8bed387..a03841b8d4d 100644
--- a/src/graph/planner/plan/Query.cpp
+++ b/src/graph/planner/plan/Query.cpp
@@ -369,6 +369,7 @@ std::unique_ptr<PlanNodeDescription> Unwind::explain() const {
 
 PlanNode* Unwind::clone() const {
   auto* newUnwind = Unwind::make(qctx_, nullptr);
+  newUnwind->setFromPipe(fromPipe_);
   newUnwind->cloneMembers(*this);
   return newUnwind;
 }
diff --git a/src/graph/planner/plan/Query.h b/src/graph/planner/plan/Query.h
index 8144e27ef5d..c10cf992f9b 100644
--- a/src/graph/planner/plan/Query.h
+++ b/src/graph/planner/plan/Query.h
@@ -841,6 +841,14 @@ class Unwind final : public SingleInputNode {
     return alias_;
   }
 
+  bool fromPipe() const {
+    return fromPipe_;
+  }
+
+  void setFromPipe(bool fromPipe) {
+    fromPipe_ = fromPipe;
+  }
+
   PlanNode* clone() const override;
   std::unique_ptr<PlanNodeDescription> explain() const override;
 
@@ -854,6 +862,7 @@ class Unwind final : public SingleInputNode {
  private:
   Expression* unwindExpr_{nullptr};
   std::string alias_;
+  bool fromPipe_{false};
 };
 
 // Sort the given record set.
diff --git a/src/graph/service/PermissionCheck.cpp b/src/graph/service/PermissionCheck.cpp
index 8939a249ae5..da0dd3789dd 100644
--- a/src/graph/service/PermissionCheck.cpp
+++ b/src/graph/service/PermissionCheck.cpp
@@ -131,6 +131,7 @@ namespace graph {
     case Sentence::Kind::kGetSubgraph:
     case Sentence::Kind::kLimit:
     case Sentence::Kind::kGroupBy:
+    case Sentence::Kind::kUnwind:
     case Sentence::Kind::kReturn: {
       return PermissionManager::canReadSchemaOrData(session, vctx);
     }
diff --git a/src/graph/validator/CMakeLists.txt b/src/graph/validator/CMakeLists.txt
index ac7dd18981e..9c8c7f66fbf 100644
--- a/src/graph/validator/CMakeLists.txt
+++ b/src/graph/validator/CMakeLists.txt
@@ -27,6 +27,7 @@ nebula_add_library(
     FindPathValidator.cpp
     LookupValidator.cpp
     MatchValidator.cpp
+    UnwindValidator.cpp
 )
 
 nebula_add_subdirectory(test)
diff --git a/src/graph/validator/FetchEdgesValidator.cpp b/src/graph/validator/FetchEdgesValidator.cpp
index bcc45c9f6fd..57b9477e82d 100644
--- a/src/graph/validator/FetchEdgesValidator.cpp
+++ b/src/graph/validator/FetchEdgesValidator.cpp
@@ -42,8 +42,7 @@ Status FetchEdgesValidator::validateEdgeName() {
 
 // Check validity of edge key(src, type, rank, dst)
 // from Input/Variable expression specified in sentence
-StatusOr<std::string> FetchEdgesValidator::validateEdgeRef(const Expression *expr,
-                                                           Value::Type type) {
+StatusOr<std::string> FetchEdgesValidator::validateEdgeRef(const Expression *expr) {
   const auto &kind = expr->kind();
   if (kind != Expression::Kind::kInputProperty && kind != EdgeExpression::Kind::kVarProperty) {
     return Status::SemanticError("`%s', only input and variable expression is acceptable",
@@ -51,12 +50,6 @@ StatusOr<std::string> FetchEdgesValidator::validateEdgeRef(const Expression *exp
   }
   auto exprType = deduceExprType(expr);
   NG_RETURN_IF_ERROR(exprType);
-  if (exprType.value() != type) {
-    std::stringstream ss;
-    ss << "`" << expr->toString() << "' should be type of " << type << ", but was "
-       << exprType.value();
-    return Status::SemanticError(ss.str());
-  }
   if (kind == Expression::Kind::kInputProperty) {
     return inputVarName_;
   }
@@ -72,13 +65,22 @@ Status FetchEdgesValidator::validateEdgeKey() {
   std::string inputVarName;
   if (sentence->isRef()) {  // edge keys from Input/Variable
     auto *srcExpr = sentence->ref()->srcid();
-    auto result = validateEdgeRef(srcExpr, vidType_);
+    auto result = validateEdgeRef(srcExpr);
     NG_RETURN_IF_ERROR(result);
     inputVarName = std::move(result).value();
 
     auto *rankExpr = sentence->ref()->rank();
     if (rankExpr->kind() != Expression::Kind::kConstant) {
-      result = validateEdgeRef(rankExpr, Value::Type::INT);
+      auto rankType = deduceExprType(rankExpr);
+      NG_RETURN_IF_ERROR(rankType);
+      if (rankType.value() != Value::Type::INT) {
+        std::stringstream ss;
+        ss << "`" << rankExpr->toString() << "' should be type of INT, but was "
+           << rankType.value();
+        return Status::SemanticError(ss.str());
+      }
+
+      result = validateEdgeRef(rankExpr);
       NG_RETURN_IF_ERROR(result);
       if (inputVarName != result.value()) {
         return Status::SemanticError(
@@ -88,7 +90,7 @@ Status FetchEdgesValidator::validateEdgeKey() {
     }
 
     auto *dstExpr = sentence->ref()->dstid();
-    result = validateEdgeRef(dstExpr, vidType_);
+    result = validateEdgeRef(dstExpr);
     NG_RETURN_IF_ERROR(result);
     if (inputVarName != result.value()) {
       return Status::SemanticError(
diff --git a/src/graph/validator/FetchEdgesValidator.h b/src/graph/validator/FetchEdgesValidator.h
index 0d1ce562640..2f652af5196 100644
--- a/src/graph/validator/FetchEdgesValidator.h
+++ b/src/graph/validator/FetchEdgesValidator.h
@@ -22,7 +22,7 @@ class FetchEdgesValidator final : public Validator {
 
   Status validateEdgeName();
 
-  StatusOr<std::string> validateEdgeRef(const Expression* expr, Value::Type type);
+  StatusOr<std::string> validateEdgeRef(const Expression* expr);
 
   Status validateEdgeKey();
 
diff --git a/src/graph/validator/UnwindValidator.cpp b/src/graph/validator/UnwindValidator.cpp
new file mode 100644
index 00000000000..6cee4c8886d
--- /dev/null
+++ b/src/graph/validator/UnwindValidator.cpp
@@ -0,0 +1,50 @@
+/* Copyright (c) 2020 vesoft inc. All rights reserved.
+ *
+ * This source code is licensed under Apache 2.0 License.
+ */
+
+#include "graph/validator/UnwindValidator.h"
+
+#include "graph/context/QueryContext.h"
+#include "graph/planner/plan/Query.h"
+#include "graph/util/ExpressionUtils.h"
+#include "parser/TraverseSentences.h"
+
+namespace nebula {
+namespace graph {
+
+Status UnwindValidator::validateImpl() {
+  auto *unwindSentence = static_cast<UnwindSentence *>(sentence_);
+  if (unwindSentence->alias().empty()) {
+    return Status::SemanticError("Expression in UNWIND must be aliased (use AS)");
+  }
+  alias_ = unwindSentence->alias();
+  unwindExpr_ = unwindSentence->expr()->clone();
+
+  if (ExpressionUtils::findAny(unwindExpr_,
+                               {Expression::Kind::kSrcProperty,
+                                Expression::Kind::kDstProperty,
+                                Expression::Kind::kVarProperty,
+                                Expression::Kind::kLabel,
+                                Expression::Kind::kAggregate,
+                                Expression::Kind::kEdgeProperty})) {
+    return Status::SemanticError("Not support `%s' in UNWIND sentence.",
+                                 unwindExpr_->toString().c_str());
+  }
+
+  auto typeStatus = deduceExprType(unwindExpr_);
+  NG_RETURN_IF_ERROR(typeStatus);
+  outputs_.emplace_back(alias_, Value::Type::__EMPTY__);
+  return Status::OK();
+}
+
+Status UnwindValidator::toPlan() {
+  auto *unwind = Unwind::make(qctx_, nullptr, unwindExpr_, alias_);
+  unwind->setColNames({alias_});
+  unwind->setFromPipe(true);
+  root_ = tail_ = unwind;
+  return Status::OK();
+}
+
+}  // namespace graph
+}  // namespace nebula
diff --git a/src/graph/validator/UnwindValidator.h b/src/graph/validator/UnwindValidator.h
new file mode 100644
index 00000000000..66aa3aaaa79
--- /dev/null
+++ b/src/graph/validator/UnwindValidator.h
@@ -0,0 +1,36 @@
+/* Copyright (c) 2020 vesoft inc. All rights reserved.
+ *
+ * This source code is licensed under Apache 2.0 License.
+ */
+
+#ifndef GRAPH_VALIDATOR_UNWINDVALIDATOR_H_
+#define GRAPH_VALIDATOR_UNWINDVALIDATOR_H_
+
+#include "graph/planner/plan/Query.h"
+#include "graph/validator/Validator.h"
+
+namespace nebula {
+
+class ObjectPool;
+
+namespace graph {
+
+class QueryContext;
+
+class UnwindValidator final : public Validator {
+ public:
+  UnwindValidator(Sentence *sentence, QueryContext *context) : Validator(sentence, context) {}
+
+  Status validateImpl() override;
+
+  Status toPlan() override;
+
+ private:
+  Expression *unwindExpr_{nullptr};
+  std::string alias_;
+};
+
+}  // namespace graph
+}  // namespace nebula
+
+#endif  // GRAPH_VALIDATOR_UNWINDVALIDATOR_H_
diff --git a/src/graph/validator/Validator.cpp b/src/graph/validator/Validator.cpp
index 58330d75132..a98dde58ad6 100644
--- a/src/graph/validator/Validator.cpp
+++ b/src/graph/validator/Validator.cpp
@@ -33,6 +33,7 @@
 #include "graph/validator/ReportError.h"
 #include "graph/validator/SequentialValidator.h"
 #include "graph/validator/SetValidator.h"
+#include "graph/validator/UnwindValidator.h"
 #include "graph/validator/UseValidator.h"
 #include "graph/validator/YieldValidator.h"
 #include "graph/visitor/DeduceTypeVisitor.h"
@@ -252,6 +253,8 @@ std::unique_ptr<Validator> Validator::makeValidator(Sentence* sentence, QueryCon
       return std::make_unique<AlterSpaceValidator>(sentence, context);
     case Sentence::Kind::kClearSpace:
       return std::make_unique<ClearSpaceValidator>(sentence, context);
+    case Sentence::Kind::kUnwind:
+      return std::make_unique<UnwindValidator>(sentence, context);
     case Sentence::Kind::kUnknown:
     case Sentence::Kind::kReturn: {
       // nothing
@@ -449,15 +452,16 @@ Status Validator::validateStarts(const VerticesClause* clause, Starts& starts) {
           src->toString().c_str());
     }
     starts.fromType = src->kind() == Expression::Kind::kInputProperty ? kPipe : kVariable;
-    auto type = deduceExprType(src);
-    if (!type.ok()) {
-      return type.status();
+    auto res = deduceExprType(src);
+    if (!res.ok()) {
+      return res.status();
     }
     auto vidType = space_.spaceDesc.vid_type_ref().value().get_type();
-    if (type.value() != SchemaUtil::propTypeToValueType(vidType)) {
+    auto& type = res.value();
+    if (type != Value::Type::__EMPTY__ && type != SchemaUtil::propTypeToValueType(vidType)) {
       std::stringstream ss;
       ss << "`" << src->toString() << "', the srcs should be type of "
-         << apache::thrift::util::enumNameSafe(vidType) << ", but was`" << type.value() << "'";
+         << apache::thrift::util::enumNameSafe(vidType) << ", but was`" << type << "'";
       return Status::SemanticError(ss.str());
     }
     starts.originalSrc = src;
diff --git a/src/graph/validator/test/GetSubgraphValidatorTest.cpp b/src/graph/validator/test/GetSubgraphValidatorTest.cpp
index 8eae1c3b757..57b4ea6324a 100644
--- a/src/graph/validator/test/GetSubgraphValidatorTest.cpp
+++ b/src/graph/validator/test/GetSubgraphValidatorTest.cpp
@@ -218,8 +218,7 @@ TEST_F(GetSubgraphValidatorTest, RefNotExist) {
         "PROP FROM $-.id YIELD vertices as nodes";
     auto result = checkResult(query);
     EXPECT_EQ(std::string(result.message()),
-              "SemanticError: `$-.id', the srcs should be type of "
-              "FIXED_STRING, but was`INT'");
+              "SemanticError: `$-.id', the srcs should be type of FIXED_STRING, but was`INT'");
   }
   {
     std::string query =
@@ -227,8 +226,7 @@ TEST_F(GetSubgraphValidatorTest, RefNotExist) {
         "FROM $a.ID YIELD edges as relationships";
     auto result = checkResult(query);
     EXPECT_EQ(std::string(result.message()),
-              "SemanticError: `$a.ID', the srcs should be type of "
-              "FIXED_STRING, but was`INT'");
+              "SemanticError: `$a.ID', the srcs should be type of FIXED_STRING, but was`INT'");
   }
   {
     std::string query =
diff --git a/src/parser/Sentence.h b/src/parser/Sentence.h
index 18b998a4d65..6afcde73784 100644
--- a/src/parser/Sentence.h
+++ b/src/parser/Sentence.h
@@ -132,6 +132,7 @@ class Sentence {
     kShowMetaLeader,
     kAlterSpace,
     kClearSpace,
+    kUnwind,
   };
 
   Kind kind() const {
diff --git a/src/parser/TraverseSentences.cpp b/src/parser/TraverseSentences.cpp
index 9114bed6124..5e21a6b3c44 100644
--- a/src/parser/TraverseSentences.cpp
+++ b/src/parser/TraverseSentences.cpp
@@ -39,6 +39,18 @@ std::string GoSentence::toString() const {
   return buf;
 }
 
+std::string UnwindSentence::toString() const {
+  std::string buf;
+  buf.reserve(256);
+
+  buf += "UNWIND ";
+  buf += expr_->toString();
+  buf += " AS ";
+  buf += alias_;
+
+  return buf;
+}
+
 LookupSentence::LookupSentence(std::string *from, WhereClause *where, YieldClause *yield)
     : Sentence(Kind::kLookup),
       from_(DCHECK_NOTNULL(from)),
diff --git a/src/parser/TraverseSentences.h b/src/parser/TraverseSentences.h
index f4044e0aae1..54d14713aa4 100644
--- a/src/parser/TraverseSentences.h
+++ b/src/parser/TraverseSentences.h
@@ -78,6 +78,33 @@ class GoSentence final : public Sentence {
   std::unique_ptr<TruncateClause> truncateClause_;
 };
 
+class UnwindSentence final : public Sentence {
+ public:
+  UnwindSentence(Expression* expr, const std::string& alias) {
+    expr_ = expr;
+    alias_ = alias;
+    kind_ = Kind::kUnwind;
+  }
+
+  Expression* expr() {
+    return expr_;
+  }
+
+  const Expression* expr() const {
+    return expr_;
+  }
+
+  const std::string& alias() const {
+    return alias_;
+  }
+
+  std::string toString() const override;
+
+ private:
+  Expression* expr_{nullptr};
+  std::string alias_;
+};
+
 class LookupSentence final : public Sentence {
  public:
   LookupSentence(std::string* from, WhereClause* where, YieldClause* yield);
diff --git a/src/parser/parser.yy b/src/parser/parser.yy
index 05e96dfa713..91f5c8e269b 100644
--- a/src/parser/parser.yy
+++ b/src/parser/parser.yy
@@ -390,7 +390,7 @@ using namespace nebula;
 %type <sentence> update_vertex_sentence update_edge_sentence
 %type <sentence> download_sentence ingest_sentence
 
-%type <sentence> traverse_sentence
+%type <sentence> traverse_sentence unwind_sentence
 %type <sentence> go_sentence match_sentence lookup_sentence find_path_sentence get_subgraph_sentence
 %type <sentence> group_by_sentence order_by_sentence limit_sentence
 %type <sentence> fetch_sentence fetch_vertices_sentence fetch_edges_sentence
@@ -1673,6 +1673,13 @@ unwind_clause
     }
     ;
 
+unwind_sentence
+    : KW_UNWIND expression KW_AS name_label {
+      $$ = new UnwindSentence($2, *$4);
+      delete $4;
+    }
+    ;
+
 with_clause
     : KW_WITH match_return_items match_order_by match_skip match_limit where_clause {
         $$ = new WithClause($2, $3, $4, $5, $6, false/*distinct*/);
@@ -2935,6 +2942,7 @@ traverse_sentence
     | show_queries_sentence { $$ = $1; }
     | kill_query_sentence { $$ = $1; }
     | describe_user_sentence { $$ = $1; }
+    | unwind_sentence { $$ = $1; }
     ;
 
 piped_sentence
diff --git a/tests/tck/features/match/PipeAndVariable.feature b/tests/tck/features/match/PipeAndVariable.feature
index 8a0f8cfb1b2..68abc31edc2 100644
--- a/tests/tck/features/match/PipeAndVariable.feature
+++ b/tests/tck/features/match/PipeAndVariable.feature
@@ -79,26 +79,108 @@ Feature: Pipe or use variable to store the lookup results
       | true | 42  |
 
   Scenario: mixed usage of cypher and ngql
+    When executing query:
+      """
+      YIELD ['Tim Duncan', 'Tony Parker'] AS a
+      | UNWIND $-.a AS b
+      | GO FROM $-.b OVER like YIELD edge AS e
+      """
+    Then the result should be, in any order:
+      | e                                                            |
+      | [:like "Tim Duncan"->"Manu Ginobili" @0 {likeness: 95}]      |
+      | [:like "Tim Duncan"->"Tony Parker" @0 {likeness: 95}]        |
+      | [:like "Tony Parker"->"LaMarcus Aldridge" @0 {likeness: 90}] |
+      | [:like "Tony Parker"->"Manu Ginobili" @0 {likeness: 95}]     |
+      | [:like "Tony Parker"->"Tim Duncan" @0 {likeness: 95}]        |
+    When executing query:
+      """
+      YIELD {a:1, b:['Tim Duncan', 'Tony Parker'], c:'Tim Duncan'} AS a
+      | YIELD $-.a.b AS b
+      | UNWIND $-.b AS c
+      | GO FROM $-.c OVER like YIELD edge AS e
+      """
+    Then the result should be, in any order:
+      | e                                                            |
+      | [:like "Tim Duncan"->"Manu Ginobili" @0 {likeness: 95}]      |
+      | [:like "Tim Duncan"->"Tony Parker" @0 {likeness: 95}]        |
+      | [:like "Tony Parker"->"LaMarcus Aldridge" @0 {likeness: 90}] |
+      | [:like "Tony Parker"->"Manu Ginobili" @0 {likeness: 95}]     |
+      | [:like "Tony Parker"->"Tim Duncan" @0 {likeness: 95}]        |
+    When executing query:
+      """
+      YIELD {a:1, b:['Tim Duncan', 'Tony Parker'], c:'Tim Duncan'} AS a
+      | YIELD $-.a.c AS b
+      | UNWIND $-.b AS c
+      | GO FROM $-.c OVER like YIELD edge AS e
+      """
+    Then the result should be, in any order:
+      | e                                                       |
+      | [:like "Tim Duncan"->"Manu Ginobili" @0 {likeness: 95}] |
+      | [:like "Tim Duncan"->"Tony Parker" @0 {likeness: 95}]   |
     When executing query:
       """
       LOOKUP ON player
       WHERE player.name == 'Tim Duncan'
       YIELD player.age as age, id(vertex) as vid
-      | UNWIND $-.vid as a RETURN a
+      | UNWIND $-.vid as a | YIELD $-.a AS a
       """
-    Then a SyntaxError should be raised at runtime: syntax error near `UNWIND'
+    Then the result should be, in any order, with relax comparison:
+      | a            |
+      | "Tim Duncan" |
     When executing query:
       """
       GET SUBGRAPH 2 STEPS FROM "Tim Duncan" BOTH like YIELD edges as e
-      | UNWIND $-.e as a RETURN a
-      """
-    Then a SyntaxError should be raised at runtime: syntax error near `UNWIND'
+      | UNWIND $-.e as a | YIELD $-.a AS a
+      """
+    Then the result should be, in any order, with relax comparison:
+      | a                                                    |
+      | [:like "Aron Baynes"->"Tim Duncan" @0 {}]            |
+      | [:like "Boris Diaw"->"Tim Duncan" @0 {}]             |
+      | [:like "Danny Green"->"Tim Duncan" @0 {}]            |
+      | [:like "Dejounte Murray"->"Tim Duncan" @0 {}]        |
+      | [:like "LaMarcus Aldridge"->"Tim Duncan" @0 {}]      |
+      | [:like "Manu Ginobili"->"Tim Duncan" @0 {}]          |
+      | [:like "Marco Belinelli"->"Tim Duncan" @0 {}]        |
+      | [:like "Shaquille O'Neal"->"Tim Duncan" @0 {}]       |
+      | [:like "Tiago Splitter"->"Tim Duncan" @0 {}]         |
+      | [:like "Tony Parker"->"Tim Duncan" @0 {}]            |
+      | [:like "Tim Duncan"->"Manu Ginobili" @0 {}]          |
+      | [:like "Tim Duncan"->"Tony Parker" @0 {}]            |
+      | [:like "Damian Lillard"->"LaMarcus Aldridge" @0 {}]  |
+      | [:like "Rudy Gay"->"LaMarcus Aldridge" @0 {}]        |
+      | [:like "LaMarcus Aldridge"->"Tony Parker" @0 {}]     |
+      | [:like "Boris Diaw"->"Tony Parker" @0 {}]            |
+      | [:like "Dejounte Murray"->"Chris Paul" @0 {}]        |
+      | [:like "Dejounte Murray"->"Danny Green" @0 {}]       |
+      | [:like "Dejounte Murray"->"James Harden" @0 {}]      |
+      | [:like "Dejounte Murray"->"Kevin Durant" @0 {}]      |
+      | [:like "Dejounte Murray"->"Kyle Anderson" @0 {}]     |
+      | [:like "Dejounte Murray"->"LeBron James" @0 {}]      |
+      | [:like "Dejounte Murray"->"Manu Ginobili" @0 {}]     |
+      | [:like "Dejounte Murray"->"Marco Belinelli" @0 {}]   |
+      | [:like "Dejounte Murray"->"Russell Westbrook" @0 {}] |
+      | [:like "Dejounte Murray"->"Tony Parker" @0 {}]       |
+      | [:like "Danny Green"->"LeBron James" @0 {}]          |
+      | [:like "Danny Green"->"Marco Belinelli" @0 {}]       |
+      | [:like "Marco Belinelli"->"Danny Green" @0 {}]       |
+      | [:like "Marco Belinelli"->"Tony Parker" @0 {}]       |
+      | [:like "Yao Ming"->"Shaquille O'Neal" @0 {}]         |
+      | [:like "Shaquille O'Neal"->"JaVale McGee" @0 {}]     |
+      | [:like "Tiago Splitter"->"Manu Ginobili" @0 {}]      |
+      | [:like "Tony Parker"->"LaMarcus Aldridge" @0 {}]     |
+      | [:like "Tony Parker"->"Manu Ginobili" @0 {}]         |
+      | [:like "James Harden"->"Russell Westbrook" @0 {}]    |
+      | [:like "Chris Paul"->"LeBron James" @0 {}]           |
+      | [:like "Russell Westbrook"->"James Harden" @0 {}]    |
     When executing query:
       """
-      FIND SHORTEST PATH FROM "Tim Duncan" TO "Yao Ming" OVER like YIELD path as p
-      | UNWIND $-.p as a RETURN a
+      FIND SHORTEST PATH FROM "Tim Duncan" TO "Tony Parker" OVER like YIELD path as p
+      | YIELD nodes($-.p) AS nodes | UNWIND $-.nodes AS a | YIELD $-.a AS a
       """
-    Then a SyntaxError should be raised at runtime: syntax error near `UNWIND'
+    Then the result should be, in any order, with relax comparison:
+      | a               |
+      | ("Tim Duncan")  |
+      | ("Tony Parker") |
     When executing query:
       """
       GO 2 STEPS FROM "Tim Duncan" OVER * YIELD dst(edge) as id
diff --git a/tests/tck/features/match/Unwind.feature b/tests/tck/features/match/Unwind.feature
index 8d9b865ce46..40e4893e853 100644
--- a/tests/tck/features/match/Unwind.feature
+++ b/tests/tck/features/match/Unwind.feature
@@ -146,7 +146,7 @@ Feature: Unwind clause
       WITH DISTINCT vid
       RETURN collect(vid) as vids
       """
-    Then a SyntaxError should be raised at runtime: syntax error near `UNWIND'
+    Then a SyntaxError should be raised at runtime: syntax error near `WITH'
     When executing query:
       """
       MATCH (a:player {name:"Tim Duncan"}) - [e:like] -> (b)