diff --git a/pkg/keyspace/keyspace.go b/pkg/keyspace/keyspace.go
index 4827587b7aa..deb6e4fc625 100644
--- a/pkg/keyspace/keyspace.go
+++ b/pkg/keyspace/keyspace.go
@@ -50,7 +50,9 @@ const (
 	// TSOKeyspaceGroupIDKey is the key for tso keyspace group id in keyspace config.
 	TSOKeyspaceGroupIDKey = "tso_keyspace_group_id"
 	// keyspacePatrolBatchSize is the batch size for keyspace assignment patrol.
-	keyspacePatrolBatchSize = 256
+	// the limit of etcd txn op is 128, keyspacePatrolBatchSize need to be less than it.
+	// See: https://github.com/etcd-io/etcd/blob/d3e43d4de6f6d9575b489dd7850a85e37e0f6b6c/server/embed/config.go#L61
+	keyspacePatrolBatchSize = 120
 )
 
 // Config is the interface for keyspace config.
diff --git a/tests/pdctl/keyspace/keyspace_group_test.go b/tests/pdctl/keyspace/keyspace_group_test.go
index 3429eb56072..28cf968e04c 100644
--- a/tests/pdctl/keyspace/keyspace_group_test.go
+++ b/tests/pdctl/keyspace/keyspace_group_test.go
@@ -95,8 +95,12 @@ func TestSplitKeyspaceGroup(t *testing.T) {
 	defer cancel()
 	re.NoError(failpoint.Enable("github.com/tikv/pd/pkg/keyspace/acceleratedAllocNodes", `return(true)`))
 	re.NoError(failpoint.Enable("github.com/tikv/pd/server/delayStartServerLoop", `return(true)`))
+	keyspaces := make([]string, 0)
+	for i := 0; i < 500; i++ {
+		keyspaces = append(keyspaces, fmt.Sprintf("keyspace_%d", i))
+	}
 	tc, err := tests.NewTestAPICluster(ctx, 3, func(conf *config.Config, serverName string) {
-		conf.Keyspace.PreAlloc = []string{"keyspace_a", "keyspace_b"}
+		conf.Keyspace.PreAlloc = keyspaces
 	})
 	re.NoError(err)
 	err = tc.RunInitialServers()
@@ -122,7 +126,7 @@ func TestSplitKeyspaceGroup(t *testing.T) {
 		output, err := pdctl.ExecuteCommand(cmd, args...)
 		re.NoError(err)
 		return strings.Contains(string(output), "Success")
-	})
+	}, testutil.WithWaitFor(20*time.Second))
 
 	re.NoError(failpoint.Disable("github.com/tikv/pd/pkg/keyspace/acceleratedAllocNodes"))
 	re.NoError(failpoint.Disable("github.com/tikv/pd/server/delayStartServerLoop"))