diff --git a/scheduler/service/service.go b/scheduler/service/service.go
index 0a159067660..cadb4189f60 100644
--- a/scheduler/service/service.go
+++ b/scheduler/service/service.go
@@ -107,8 +107,7 @@ func (s *Service) RegisterPeerTask(ctx context.Context, req *rpcscheduler.PeerTa
 			fallthrough
 		case base.SizeScope_SMALL:
 			peer.Log.Info("task size scope is small")
-			// If the file is registered as a small type,
-			// there is no need to build a tree, just find the parent and return
+			// There is no need to build a tree, just find the parent and return
 			parent, ok := s.scheduler.FindParent(ctx, peer, set.NewSafeSet())
 			if !ok {
 				peer.Log.Warn("task size scope is small and it can not select parent")
@@ -124,6 +123,22 @@ func (s *Service) RegisterPeerTask(ctx context.Context, req *rpcscheduler.PeerTa
 				}, nil
 			}
 
+			// When task size scope is small, parent must be downloaded successfully
+			// before returning to the parent directly
+			if !parent.FSM.Is(resource.PeerStateSucceeded) {
+				peer.Log.Infof("task size scope is small and download state %s is not PeerStateSucceeded", parent.FSM.Current())
+				if err := peer.FSM.Event(resource.PeerEventRegisterNormal); err != nil {
+					dferr := dferrors.New(base.Code_SchedError, err.Error())
+					peer.Log.Errorf("peer %s register is failed: %v", req.PeerId, err)
+					return nil, dferr
+				}
+
+				return &rpcscheduler.RegisterResult{
+					TaskId:    task.ID,
+					SizeScope: base.SizeScope_NORMAL,
+				}, nil
+			}
+
 			firstPiece, ok := task.LoadPiece(0)
 			if !ok {
 				peer.Log.Warn("task size scope is small and it can not get first piece")
diff --git a/scheduler/service/service_test.go b/scheduler/service/service_test.go
index 0959b9394c9..0f2deff96a4 100644
--- a/scheduler/service/service_test.go
+++ b/scheduler/service/service_test.go
@@ -346,6 +346,46 @@ func TestService_RegisterPeerTask(t *testing.T) {
 				assert.True(peer.FSM.Is(resource.PeerStateReceivedNormal))
 			},
 		},
+		{
+			name: "task scope size is SizeScope_SMALL and load piece error, parent state is PeerStateRunning",
+			req: &rpcscheduler.PeerTaskRequest{
+				PeerHost: &rpcscheduler.PeerHost{
+					Uuid: mockRawHost.Uuid,
+				},
+			},
+			mock: func(
+				req *rpcscheduler.PeerTaskRequest, mockPeer *resource.Peer, mockCDNPeer *resource.Peer,
+				scheduler scheduler.Scheduler, res resource.Resource, hostManager resource.HostManager, taskManager resource.TaskManager, peerManager resource.PeerManager,
+				ms *mocks.MockSchedulerMockRecorder, mr *resource.MockResourceMockRecorder, mh *resource.MockHostManagerMockRecorder, mt *resource.MockTaskManagerMockRecorder, mp *resource.MockPeerManagerMockRecorder,
+			) {
+				mockPeer.Task.FSM.SetState(resource.TaskStateSucceeded)
+				mockPeer.Task.StorePeer(mockCDNPeer)
+				mockPeer.Task.ContentLength.Store(129)
+				mockPeer.Task.StorePiece(&base.PieceInfo{
+					PieceNum: 0,
+				})
+				mockPeer.Task.TotalPieceCount.Store(1)
+				mockPeer.FSM.SetState(resource.PeerStatePending)
+				mockCDNPeer.FSM.SetState(resource.PeerStateRunning)
+
+				gomock.InOrder(
+					mr.TaskManager().Return(taskManager).Times(1),
+					mt.LoadOrStore(gomock.Any()).Return(mockPeer.Task, true).Times(1),
+					mr.HostManager().Return(hostManager).Times(1),
+					mh.Load(gomock.Eq(mockPeer.Host.ID)).Return(mockPeer.Host, true).Times(1),
+					mr.PeerManager().Return(peerManager).Times(1),
+					mp.LoadOrStore(gomock.Any()).Return(mockPeer, true).Times(1),
+					ms.FindParent(gomock.Any(), gomock.Any(), gomock.Any()).Return(mockCDNPeer, true).Times(1),
+				)
+			},
+			expect: func(t *testing.T, peer *resource.Peer, result *rpcscheduler.RegisterResult, err error) {
+				assert := assert.New(t)
+				assert.NoError(err)
+				assert.Equal(result.TaskId, peer.Task.ID)
+				assert.Equal(result.SizeScope, base.SizeScope_NORMAL)
+				assert.True(peer.FSM.Is(resource.PeerStateReceivedNormal))
+			},
+		},
 		{
 			name: "task scope size is SizeScope_SMALL and load piece error, peer state is PeerStateFailed",
 			req: &rpcscheduler.PeerTaskRequest{
@@ -366,6 +406,8 @@ func TestService_RegisterPeerTask(t *testing.T) {
 				})
 				mockPeer.Task.TotalPieceCount.Store(1)
 				mockPeer.FSM.SetState(resource.PeerStateFailed)
+				mockCDNPeer.FSM.SetState(resource.PeerStateSucceeded)
+
 				gomock.InOrder(
 					mr.TaskManager().Return(taskManager).Times(1),
 					mt.LoadOrStore(gomock.Any()).Return(mockPeer.Task, true).Times(1),
@@ -403,6 +445,8 @@ func TestService_RegisterPeerTask(t *testing.T) {
 				})
 				mockPeer.Task.TotalPieceCount.Store(1)
 				mockPeer.FSM.SetState(resource.PeerStateFailed)
+				mockCDNPeer.FSM.SetState(resource.PeerStateSucceeded)
+
 				gomock.InOrder(
 					mr.TaskManager().Return(taskManager).Times(1),
 					mt.LoadOrStore(gomock.Any()).Return(mockPeer.Task, true).Times(1),
@@ -439,6 +483,8 @@ func TestService_RegisterPeerTask(t *testing.T) {
 					PieceNum: 0,
 				})
 				mockPeer.Task.TotalPieceCount.Store(1)
+				mockCDNPeer.FSM.SetState(resource.PeerStateSucceeded)
+
 				gomock.InOrder(
 					mr.TaskManager().Return(taskManager).Times(1),
 					mt.LoadOrStore(gomock.Any()).Return(mockPeer.Task, true).Times(1),