diff --git a/src/gausskernel/runtime/executor/nodeModifyTable.cpp b/src/gausskernel/runtime/executor/nodeModifyTable.cpp
index 99a2cc66b6b7858a8e1ed143dde35dfd776e78a6..b3821d0a80baf8f5fa6eabcf4d8b0d6dec4c0534 100644
--- a/src/gausskernel/runtime/executor/nodeModifyTable.cpp
+++ b/src/gausskernel/runtime/executor/nodeModifyTable.cpp
@@ -2200,14 +2200,6 @@ TupleTableSlot* ExecUpdate(ItemPointer tupleid,
         bool update_indexes = false;
         LockTupleMode lockmode;
 
-        /* acquire Form_pg_attrdef ad_on_update */
-        if (result_relation_desc->rd_att->constr && result_relation_desc->rd_att->constr->has_on_update) {
-            bool update_fix_result =  ExecComputeStoredUpdateExpr(result_rel_info, estate, slot, tuple, CMD_UPDATE, tupleid, oldPartitionOid, bucketid);
-            if (!update_fix_result) {
-                tuple = slot->tts_tuple;
-            }
-        }
-
         /*
          * Check the constraints of the tuple
          *
@@ -2220,6 +2212,14 @@ TupleTableSlot* ExecUpdate(ItemPointer tupleid,
         Assert(RELATION_HAS_BUCKET(result_relation_desc) == (bucketid != InvalidBktId));
 lreplace:
 
+        /* acquire Form_pg_attrdef ad_on_update */
+        if (result_relation_desc->rd_att->constr && result_relation_desc->rd_att->constr->has_on_update) {
+            bool update_fix_result =  ExecComputeStoredUpdateExpr(result_rel_info, estate, slot, tuple, CMD_UPDATE, tupleid, oldPartitionOid, bucketid);
+            if (!update_fix_result) {
+                tuple = slot->tts_tuple;
+            }
+        }
+
         /*
          * Compute stored generated columns
          */
diff --git a/src/test/regress/expected/on_update_session1.out b/src/test/regress/expected/on_update_session1.out
new file mode 100644
index 0000000000000000000000000000000000000000..e19fdab6006e2c9ee897ecbaa006ce1baddcbd78
--- /dev/null
+++ b/src/test/regress/expected/on_update_session1.out
@@ -0,0 +1,25 @@
+create database mysql_test dbcompatibility 'B';
+\c mysql_test
+create table tb666(c1 timestamp default current_timestamp on update current_timestamp, c2 int, c3 timestamp generated always as(c1+c2) stored);
+insert into tb666 values(default, 1);
+select * from tb666;
+               c1               | c2 |               c3               
+--------------------------------+----+--------------------------------
+--?.*
+(1 row)
+
+begin;
+update tb666 set c2 = 2;
+select * from tb666;
+               c1                | c2 |               c3               
+---------------------------------+----+--------------------------------
+--?.*
+(1 row)
+
+select pg_sleep(2);
+ pg_sleep 
+----------
+ 
+(1 row)
+
+commit;
diff --git a/src/test/regress/expected/on_update_session2.out b/src/test/regress/expected/on_update_session2.out
new file mode 100644
index 0000000000000000000000000000000000000000..fef93c808da2974f8508605ec20669ff77c53ef3
--- /dev/null
+++ b/src/test/regress/expected/on_update_session2.out
@@ -0,0 +1,14 @@
+select pg_sleep(2);
+ pg_sleep 
+----------
+ 
+(1 row)
+
+\c mysql_test
+update tb666 set c2 = 3;
+select * from tb666;
+               c1                | c2 |               c3                
+---------------------------------+----+---------------------------------
+--?.*
+(1 row)
+
diff --git a/src/test/regress/parallel_schedule0 b/src/test/regress/parallel_schedule0
index c5efdcb4e124ad54e47ae90fc96e4b0040f22aa2..6e5ca738224aca93c09b9e67f034e2b2268ae076 100644
--- a/src/test/regress/parallel_schedule0
+++ b/src/test/regress/parallel_schedule0
@@ -1088,3 +1088,5 @@ test: user_host_test
 
 # test for new_expr_by_flatten
 test: enable_expr_fusion_flatten
+# test for on update timestamp and generated column
+test: on_update_session1 on_update_session2
diff --git a/src/test/regress/sql/on_update_session1.sql b/src/test/regress/sql/on_update_session1.sql
new file mode 100644
index 0000000000000000000000000000000000000000..08293e6a0b831d7e5a154c541d1e58c1c520499a
--- /dev/null
+++ b/src/test/regress/sql/on_update_session1.sql
@@ -0,0 +1,10 @@
+create database mysql_test dbcompatibility 'B';
+\c mysql_test
+create table tb666(c1 timestamp default current_timestamp on update current_timestamp, c2 int, c3 timestamp generated always as(c1+c2) stored);
+insert into tb666 values(default, 1);
+select * from tb666;
+begin;
+update tb666 set c2 = 2;
+select * from tb666;
+select pg_sleep(2);
+commit;
\ No newline at end of file
diff --git a/src/test/regress/sql/on_update_session2.sql b/src/test/regress/sql/on_update_session2.sql
new file mode 100644
index 0000000000000000000000000000000000000000..7f982f258ff62f5196ad881eaebf52806d731c6c
--- /dev/null
+++ b/src/test/regress/sql/on_update_session2.sql
@@ -0,0 +1,4 @@
+select pg_sleep(2);
+\c mysql_test
+update tb666 set c2 = 3;
+select * from tb666;
\ No newline at end of file