diff --git a/pkg/manager/member/pvc_resizer.go b/pkg/manager/member/pvc_resizer.go
index 55c13e05ca3..baab7f6eec9 100644
--- a/pkg/manager/member/pvc_resizer.go
+++ b/pkg/manager/member/pvc_resizer.go
@@ -59,6 +59,7 @@ import (
 // - If the feature `ExpandInUsePersistentVolumes` is not enabled or the volume
 //   plugin does not support, the pod referencing the volume must be deleted and
 //   recreted after the `FileSystemResizePending` condition becomes true.
+// - Shrinking volumes is not supported.
 //
 type PVCResizerInterface interface {
 	Resize(*v1alpha1.TidbCluster) error
@@ -169,12 +170,14 @@ func (p *pvcResizer) patchPVCs(ns string, selector labels.Selector, storageReque
 			klog.Warningf("Storage Class %q used by PVC %s/%s does not support volume expansion, skipped", *pvc.Spec.StorageClassName, pvc.Namespace, pvc.Name)
 			continue
 		}
-		if currentRequest, ok := pvc.Spec.Resources.Requests[corev1.ResourceStorage]; !ok || currentRequest != storageRequest {
+		if currentRequest, ok := pvc.Spec.Resources.Requests[corev1.ResourceStorage]; !ok || storageRequest.Cmp(currentRequest) > 0 {
 			_, err = p.kubeCli.CoreV1().PersistentVolumeClaims(pvc.Namespace).Patch(pvc.Name, types.MergePatchType, mergePatch)
 			if err != nil {
 				return err
 			}
 			klog.V(2).Infof("PVC %s/%s storage request is updated from %s to %s", pvc.Namespace, pvc.Name, currentRequest.String(), storageRequest.String())
+		} else if storageRequest.Cmp(currentRequest) < 0 {
+			klog.Warningf("PVC %s/%s/ storage request cannot be shrinked (%s to %s), skipped", pvc.Namespace, pvc.Name, currentRequest.String(), storageRequest.String())
 		} else {
 			klog.V(4).Infof("PVC %s/%s storage request is already %s, skipped", pvc.Namespace, pvc.Name, storageRequest.String())
 		}
diff --git a/pkg/manager/member/pvc_resizer_test.go b/pkg/manager/member/pvc_resizer_test.go
index e0ac555393b..58743b36980 100644
--- a/pkg/manager/member/pvc_resizer_test.go
+++ b/pkg/manager/member/pvc_resizer_test.go
@@ -28,14 +28,9 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/informers"
 	"k8s.io/client-go/kubernetes/fake"
-	"k8s.io/klog"
 	"k8s.io/utils/pointer"
 )
 
-func init() {
-	klog.InitFlags(nil)
-}
-
 func newPVCWithStorage(name string, component string, storaegClass, storageRequest string) *v1.PersistentVolumeClaim {
 	return &v1.PersistentVolumeClaim{
 		ObjectMeta: metav1.ObjectMeta{
@@ -257,6 +252,32 @@ func TestPVCResizer(t *testing.T) {
 			},
 			wantErr: nil,
 		},
+		{
+			name: "shrinking is not supported",
+			tc: &v1alpha1.TidbCluster{
+				ObjectMeta: metav1.ObjectMeta{
+					Namespace: v1.NamespaceDefault,
+					Name:      "tc",
+				},
+				Spec: v1alpha1.TidbClusterSpec{
+					PD: &v1alpha1.PDSpec{
+						ResourceRequirements: v1.ResourceRequirements{
+							Requests: v1.ResourceList{
+								v1.ResourceStorage: resource.MustParse("1Gi"),
+							},
+						},
+					},
+				},
+			},
+			sc: newStorageClass("sc", false),
+			pvcs: []*v1.PersistentVolumeClaim{
+				newPVCWithStorage("pd-0", label.PDLabelVal, "sc", "2Gi"),
+			},
+			wantPVCs: []*v1.PersistentVolumeClaim{
+				newPVCWithStorage("pd-0", label.PDLabelVal, "sc", "2Gi"),
+			},
+			wantErr: nil,
+		},
 	}
 
 	for _, tt := range tests {