diff --git a/src/gausskernel/optimizer/commands/functioncmds.cpp b/src/gausskernel/optimizer/commands/functioncmds.cpp
index f977a725c..5f37e8ab4 100755
--- a/src/gausskernel/optimizer/commands/functioncmds.cpp
+++ b/src/gausskernel/optimizer/commands/functioncmds.cpp
@@ -98,40 +98,6 @@ static const int PRO_RETURN_SET_COST = 1000;
  * validator, so as not to produce a NOTICE and then an ERROR for the same
  * condition.)
  */
-static void CheckIsSerialType(TypeName* t)
-{
-    bool isSerial = false;
-    /* Check for SERIAL pseudo-types */
-    if (t && list_length(t->names) == 1 && t->pct_type == false) {
-        char* typname = strVal(linitial(t->names));
-
-        if (strcmp(typname, "smallserial") == 0 || strcmp(typname, "serial2") == 0) {
-            isSerial = true;
-            t->names = NIL;
-            t->typeOid = INT2OID;
-        } else if (strcmp(typname, "serial") == 0 || strcmp(typname, "serial4") == 0) {
-            isSerial = true;
-            t->names = NIL;
-            t->typeOid = INT4OID;
-        } else if (strcmp(typname, "bigserial") == 0 || strcmp(typname, "serial8") == 0) {
-            isSerial = true;
-            t->names = NIL;
-            t->typeOid = INT8OID;
-        } 
-
-        if (isSerial && t->arrayBounds != NIL) {
-            /*
-             * We have to reject "serial[]" explicitly, because once we've set
-             * typeid, LookupTypeName won't notice arrayBounds.  We don't need any
-             * special coding for serial(typmod) though.
-            */
-            ereport(ERROR,
-                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-                    errmsg("array of serial is not implemented")));
-        }
-    }
-}
-
 static void compute_return_type(
     TypeName* returnType, Oid languageOid, Oid* prorettype_p, bool* returnsSet_p, bool fenced)
 {
@@ -145,8 +111,6 @@ static void compute_return_type(
      */
     bool isalter = false;
 
-    CheckIsSerialType(returnType);
-
     typtup = LookupTypeName(NULL, returnType, NULL);
     /*
      * If the type is relation, then we check
@@ -285,8 +249,6 @@ static void examine_parameter_list(List* parameters, Oid languageOid, const char
         Type typtup;
         AclResult aclresult;
 
-        CheckIsSerialType(t);
-
         typtup = LookupTypeName(NULL, t, NULL);
         /*
          * If the type is relation, then we check