diff --git a/pkg/apis/pingcap/v1alpha1/defaulting/tidbcluster.go b/pkg/apis/pingcap/v1alpha1/defaulting/tidbcluster.go
index a3ce0d68522..2c2fa69f38e 100644
--- a/pkg/apis/pingcap/v1alpha1/defaulting/tidbcluster.go
+++ b/pkg/apis/pingcap/v1alpha1/defaulting/tidbcluster.go
@@ -51,9 +51,6 @@ func setTidbClusterSpecDefault(tc *v1alpha1.TidbCluster) {
 }
 
 func setTidbSpecDefault(tc *v1alpha1.TidbCluster) {
-	if tc.Spec.TiDB.Config == nil {
-		tc.Spec.TiDB.Config = &v1alpha1.TiDBConfig{}
-	}
 	if len(tc.Spec.Version) > 0 || tc.Spec.TiDB.Version != nil {
 		if tc.Spec.TiDB.BaseImage == "" {
 			tc.Spec.TiDB.BaseImage = defaultTiDBImage
@@ -62,9 +59,6 @@ func setTidbSpecDefault(tc *v1alpha1.TidbCluster) {
 }
 
 func setTikvSpecDefault(tc *v1alpha1.TidbCluster) {
-	if tc.Spec.TiKV.Config == nil {
-		tc.Spec.TiKV.Config = &v1alpha1.TiKVConfig{}
-	}
 	if len(tc.Spec.Version) > 0 || tc.Spec.TiKV.Version != nil {
 		if tc.Spec.TiKV.BaseImage == "" {
 			tc.Spec.TiKV.BaseImage = defaultTiKVImage
@@ -73,9 +67,6 @@ func setTikvSpecDefault(tc *v1alpha1.TidbCluster) {
 }
 
 func setPdSpecDefault(tc *v1alpha1.TidbCluster) {
-	if tc.Spec.PD.Config == nil {
-		tc.Spec.PD.Config = &v1alpha1.PDConfig{}
-	}
 	if len(tc.Spec.Version) > 0 || tc.Spec.PD.Version != nil {
 		if tc.Spec.PD.BaseImage == "" {
 			tc.Spec.PD.BaseImage = defaultPDImage
diff --git a/pkg/apis/pingcap/v1alpha1/validation/validation.go b/pkg/apis/pingcap/v1alpha1/validation/validation.go
index 728f6b80fcb..39855db7a20 100644
--- a/pkg/apis/pingcap/v1alpha1/validation/validation.go
+++ b/pkg/apis/pingcap/v1alpha1/validation/validation.go
@@ -88,15 +88,6 @@ func validateNewTidbClusterSpec(spec *v1alpha1.TidbClusterSpec, path *field.Path
 	if spec.PD.Image != "" {
 		allErrs = append(allErrs, field.Invalid(path.Child("pd.image"), spec.PD.Image, "image has been deprecated, use baseImage instead"))
 	}
-	if spec.TiDB.Config == nil {
-		allErrs = append(allErrs, field.Invalid(path.Child("tidb.config"), spec.TiDB.Config, "tidb.config must not be nil"))
-	}
-	if spec.TiKV.Config == nil {
-		allErrs = append(allErrs, field.Invalid(path.Child("tikv.config"), spec.TiKV.Config, "tidb.config must not be nil"))
-	}
-	if spec.PD.Config == nil {
-		allErrs = append(allErrs, field.Invalid(path.Child("pd.config"), spec.PD.Config, "tidb.config must not be nil"))
-	}
 	return allErrs
 }
 
diff --git a/tests/e2e/tidbcluster/serial.go b/tests/e2e/tidbcluster/serial.go
index 58619678dbb..74c9a6da183 100644
--- a/tests/e2e/tidbcluster/serial.go
+++ b/tests/e2e/tidbcluster/serial.go
@@ -590,9 +590,6 @@ var _ = ginkgo.Describe("[tidb-operator][Serial]", func() {
 			if empty, err := gomega.BeEmpty().Match(newTC.Spec.TiDB.BaseImage); empty {
 				e2elog.Failf("Expected tidb.baseImage has default value set, %v", err)
 			}
-			if isNil, err := gomega.BeNil().Match(newTC.Spec.TiDB.Config); isNil {
-				e2elog.Failf("Expected tidb.config has default value set, %v", err)
-			}
 
 			ginkgo.By("Validating should reject illegal update")
 			newTC.Labels = map[string]string{
@@ -601,8 +598,10 @@ var _ = ginkgo.Describe("[tidb-operator][Serial]", func() {
 			_, err = cli.PingcapV1alpha1().TidbClusters(ns).Update(newTC)
 			framework.ExpectError(err, "Could not set instance label with value other than cluster name")
 
-			newTC.Spec.PD.Config.Replication = &v1alpha1.PDReplicationConfig{
-				MaxReplicas: func() *uint64 { i := uint64(5); return &i }(),
+			newTC.Spec.PD.Config = &v1alpha1.PDConfig{
+				Replication: &v1alpha1.PDReplicationConfig{
+					MaxReplicas: func() *uint64 { i := uint64(5); return &i }(),
+				},
 			}
 			_, err = cli.PingcapV1alpha1().TidbClusters(ns).Update(newTC)
 			framework.ExpectError(err, "PD replication config is immutable through CR")