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
diff --git a/src/test/regress/expected/test_serial.out b/src/test/regress/expected/test_serial.out
deleted file mode 100644
index d6bd790bc..000000000
--- a/src/test/regress/expected/test_serial.out
+++ /dev/null
@@ -1,62 +0,0 @@
---
--- testserial
---
-create table tbl_small_serial(a smallserial, b varchar(2));
-NOTICE:  CREATE TABLE will create implicit sequence "tbl_small_serial_a_seq" for serial column "tbl_small_serial.a"
-
-insert into tbl_small_serial(b) values ('aa');
-
-create table tbl_serial(a serial, b varchar(2));
-NOTICE:  CREATE TABLE will create implicit sequence "tbl_serial_a_seq" for serial column "tbl_serial.a"
-
-insert into tbl_serial(b) values ('bb');
-
-create table tbl_big_serial(a bigserial, b varchar(2));
-NOTICE:  CREATE TABLE will create implicit sequence "tbl_big_serial_a_seq" for serial column "tbl_big_serial.a"
-
-insert into tbl_big_serial(b) values ('cc');
-
-CREATE  FUNCTION h_testfun6 (c_SMALLSERIAL SMALLSERIAL) RETURNS SMALLSERIAL   AS $$
-        BEGIN
-                RETURN c_SMALLSERIAL;
-        END;
-$$ LANGUAGE plpgsql;
-CREATE  FUNCTION h_testfun7 (c_SERIAL SERIAL) RETURNS SERIAL   AS $$
-        BEGIN
-                RETURN c_SERIAL ;
-        END;
-$$ LANGUAGE plpgsql;
-CREATE  FUNCTION h_testfun8 (c_BIGSERIAL BIGSERIAL) RETURNS BIGSERIAL   AS $$
-        BEGIN
-                RETURN c_BIGSERIAL ;
-        END;
-$$ LANGUAGE plpgsql;
-
-SELECT h_testfun6((SELECT a from  tbl_small_serial));
- h_testfun6 
-------------
-          1
-(1 row)
-
-
-SELECT h_testfun7((SELECT a from  tbl_serial));
- h_testfun7 
-------------
-          1
-(1 row)
-
-
-SELECT h_testfun8((SELECT a from  tbl_big_serial));
- h_testfun8 
-------------
-          1
-(1 row)
-
-
-drop table tbl_small_serial;
-drop table tbl_serial;
-drop table tbl_big_serial;
-
-drop function h_testfun6;
-drop function h_testfun7;
-drop function h_testfun8;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 8989683f4..789e55a56 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -526,9 +526,6 @@ test: vec_sonic_hashjoin_number_prepare
 test: vec_sonic_hashjoin_number_nospill
 #test: hw_pwd_complexity
 
-# test serial function
-test: test_serial
-
 test: timeout
 test: dml
 #test: iud
diff --git a/src/test/regress/sql/test_serial.sql b/src/test/regress/sql/test_serial.sql
deleted file mode 100644
index 568d25121..000000000
--- a/src/test/regress/sql/test_serial.sql
+++ /dev/null
@@ -1,44 +0,0 @@
---
--- testserial
---
-create table tbl_small_serial(a smallserial, b varchar(2));
-
-insert into tbl_small_serial(b) values ('aa');
-
-create table tbl_serial(a serial, b varchar(2));
-
-insert into tbl_serial(b) values ('bb');
-
-create table tbl_big_serial(a bigserial, b varchar(2));
-
-insert into tbl_big_serial(b) values ('cc');
-
-CREATE  FUNCTION h_testfun6 (c_SMALLSERIAL SMALLSERIAL) RETURNS SMALLSERIAL   AS $$
-        BEGIN
-                RETURN c_SMALLSERIAL ;
-        END;
-$$ LANGUAGE plpgsql;
-CREATE  FUNCTION h_testfun7 (c_SERIAL SERIAL) RETURNS SERIAL   AS $$
-        BEGIN
-                RETURN c_SERIAL ;
-        END;
-$$ LANGUAGE plpgsql;
-CREATE  FUNCTION h_testfun8 (c_BIGSERIAL BIGSERIAL) RETURNS BIGSERIAL   AS $$
-        BEGIN
-                RETURN c_BIGSERIAL ;
-        END;
-$$ LANGUAGE plpgsql;
-
-SELECT h_testfun6((SELECT a from  tbl_small_serial));
-
-SELECT h_testfun7((SELECT a from  tbl_serial));
-
-SELECT h_testfun8((SELECT a from  tbl_big_serial));
-
-drop table tbl_small_serial;
-drop table tbl_serial;
-drop table tbl_big_serial;
-
-drop function h_testfun6;
-drop function h_testfun7;
-drop function h_testfun8;
\ No newline at end of file