diff --git a/dm/config/task_test.go b/dm/config/task_test.go
index 06c9b6b7f7..b040ebdb9c 100644
--- a/dm/config/task_test.go
+++ b/dm/config/task_test.go
@@ -15,9 +15,12 @@ package config
 
 import (
 	. "github.com/pingcap/check"
+	"io/ioutil"
+	"path"
 )
 
-var errorTaskConfig1 = `---
+func (t *testConfig) TestInvalidTaskConfig(c *C) {
+	var errorTaskConfig1 = `---
 name: test
 task-mode: all
 is-sharding: true
@@ -43,7 +46,7 @@ mysql-instances:
     loader-config-name: "global"
     syncer-config-name: "global"
 `
-var errorTaskConfig2 = `---
+	var errorTaskConfig2 = `---
 name: test
 name: test1
 task-mode: all
@@ -69,8 +72,6 @@ mysql-instances:
     loader-config-name: "global"
     syncer-config-name: "global"
 `
-
-func (t *testConfig) TestInvalidTaskConfig(c *C) {
 	taskConfig := NewTaskConfig()
 	err := taskConfig.Decode(errorTaskConfig1)
 	// field server-id is not a member of TaskConfig
@@ -81,4 +82,38 @@ func (t *testConfig) TestInvalidTaskConfig(c *C) {
 	// field name duplicate
 	c.Check(err, NotNil)
 	c.Assert(err, ErrorMatches, "*line 3: field name already set in type config.TaskConfig*")
+
+	filepath := path.Join(c.MkDir(), "test_invalid_task.yaml")
+	configContent := []byte(`---
+aaa: xxx
+name: test
+task-mode: all
+is-sharding: true
+meta-schema: "dm_meta"
+remove-meta: false
+enable-heartbeat: true
+timezone: "Asia/Shanghai"
+ignore-checking-items: ["all"]
+`)
+	err = ioutil.WriteFile(filepath, configContent, 0644)
+	err = taskConfig.DecodeFile(filepath)
+	c.Assert(err, NotNil)
+	c.Assert(err, ErrorMatches, "*line 2: field aaa not found in type config.TaskConfig*")
+
+	filepath = path.Join(c.MkDir(), "test_invalid_task.yaml")
+	configContent = []byte(`---
+name: test
+task-mode: all
+task-mode: all
+is-sharding: true
+meta-schema: "dm_meta"
+remove-meta: false
+enable-heartbeat: true
+timezone: "Asia/Shanghai"
+ignore-checking-items: ["all"]
+`)
+	err = ioutil.WriteFile(filepath, configContent, 0644)
+	err = taskConfig.DecodeFile(filepath)
+	c.Assert(err, NotNil)
+	c.Assert(err, ErrorMatches, "*line 4: field task-mode already set in type config.TaskConfig*")
 }