diff --git a/source/libs/planner/src/planOptimizer.c b/source/libs/planner/src/planOptimizer.c
index b179c58ee1..39024731ed 100644
--- a/source/libs/planner/src/planOptimizer.c
+++ b/source/libs/planner/src/planOptimizer.c
@@ -3501,15 +3501,17 @@ static int32_t eliminateProjOptFindProjPrefixWithOrderCheck(SProjectLogicNode* p
       *orderMatch = false;
       break;
     }
-    SNode* pNew = NULL;
-    code = nodesCloneNode(pChildTarget, &pNew);
-    if (TSDB_CODE_SUCCESS == code) {
-      code = nodesListMakeStrictAppend(pNewChildTargets, pNew);
-    }
-    if (TSDB_CODE_SUCCESS != code && pNewChildTargets) {
-      nodesDestroyList(*pNewChildTargets);
-      *pNewChildTargets = NULL;
-      break;
+    if (pNewChildTargets) {
+      SNode* pNew = NULL;
+      code = nodesCloneNode(pChildTarget, &pNew);
+      if (TSDB_CODE_SUCCESS == code) {
+        code = nodesListMakeStrictAppend(pNewChildTargets, pNew);
+      }
+      if (TSDB_CODE_SUCCESS != code && pNewChildTargets) {
+        nodesDestroyList(*pNewChildTargets);
+        *pNewChildTargets = NULL;
+        break;
+      }
     }
   }
   return code;
@@ -3543,6 +3545,8 @@ static int32_t eliminateProjOptimizeImpl(SOptimizeContext* pCxt, SLogicSubplan*
   int32_t     code = 0;
   bool        isSetOpProj = false;
   bool        orderMatch = false;
+  bool        sizeMatch = LIST_LENGTH(pProjectNode->pProjections) == LIST_LENGTH(pChild->pTargets);
+  bool        needReplaceTargets = true;
 
   if (NULL == pProjectNode->node.pParent) {
     SNodeList* pNewChildTargets = NULL;
@@ -3553,7 +3557,12 @@ static int32_t eliminateProjOptimizeImpl(SOptimizeContext* pCxt, SLogicSubplan*
       // For sql: select ... from (select ... union all select ...);
       // When eliminating the outer proj (the outer select), we have to make sure that the outer proj projections and
       // union all project targets have same columns in the same order. See detail in TD-30188
-      code = eliminateProjOptFindProjPrefixWithOrderCheck(pProjectNode, (SProjectLogicNode*)pChild, &pNewChildTargets, &orderMatch);
+      code = eliminateProjOptFindProjPrefixWithOrderCheck(pProjectNode, (SProjectLogicNode*)pChild,
+                                                          sizeMatch ? NULL : &pNewChildTargets, &orderMatch);
+      if (TSDB_CODE_SUCCESS == code && sizeMatch && orderMatch) {
+        pNewChildTargets = pChild->pTargets;
+        needReplaceTargets = false;
+      }
     } else {
       FOREACH(pProjection, pProjectNode->pProjections) {
         FOREACH(pChildTarget, pChild->pTargets) {
@@ -3577,10 +3586,12 @@ static int32_t eliminateProjOptimizeImpl(SOptimizeContext* pCxt, SLogicSubplan*
     }
 
     if (eliminateProjOptCanChildConditionUseChildTargets(pChild, pNewChildTargets) && (!isSetOpProj || orderMatch)) {
-      nodesDestroyList(pChild->pTargets);
-      pChild->pTargets = pNewChildTargets;
+      if (needReplaceTargets) {
+        nodesDestroyList(pChild->pTargets);
+        pChild->pTargets = pNewChildTargets;
+      }
     } else {
-      nodesDestroyList(pNewChildTargets);
+      if (needReplaceTargets) nodesDestroyList(pNewChildTargets);
       OPTIMIZE_FLAG_SET_MASK(pProjectNode->node.optimizedFlag, OPTIMIZE_FLAG_ELIMINATE_PROJ);
       pCxt->optimized = true;
       return TSDB_CODE_SUCCESS;
@@ -3603,10 +3614,10 @@ static int32_t eliminateProjOptimizeImpl(SOptimizeContext* pCxt, SLogicSubplan*
     NODES_CLEAR_LIST(pProjectNode->node.pChildren);
     nodesDestroyNode((SNode*)pProjectNode);
     // if pChild is a project logic node, remove its projection which is not reference by its target.
-    alignProjectionWithTarget(pChild);
-    if (isSetOpProj && orderMatch) {
+    if (needReplaceTargets) {
+      alignProjectionWithTarget(pChild);
       // Since we have eliminated the outer proj, we need to push down the new targets to the children of the set operation.
-      code = eliminateProjOptPushTargetsToSetOpChildren((SProjectLogicNode*)pChild);
+      if (isSetOpProj && orderMatch && !sizeMatch) code = eliminateProjOptPushTargetsToSetOpChildren((SProjectLogicNode*)pChild);
     }
   }
   pCxt->optimized = true;
diff --git a/tests/system-test/2-query/union.py b/tests/system-test/2-query/union.py
index b74db0104d..5104489592 100644
--- a/tests/system-test/2-query/union.py
+++ b/tests/system-test/2-query/union.py
@@ -399,7 +399,12 @@ class TDTestCase:
         tdSql.query(sql, queryTimes=1)
         tdSql.checkRows(6)
         tdSql.checkCols(3)
-        tdSql.execute("drop database ep_iot")
+
+        sql = "select scdw_code, scdw_name, jzmc, fdgl, jzzt,ts from ((select '01072016' as scdw_code, '盛鲁电厂' as scdw_name, '机组1' as jzmc, last(jz1fdjyggl) as fdgl, '填报' as jzzt, last(ts) as ts from ep_iot.sldc_dp) union all ( select '01072016' as scdw_code, '盛鲁电厂' as scdw_name, '机组2' as jzmc, last(jz2fdjyggl) as fdgl, '填报' as jzzt, last(ts) as ts from ep_iot.sldc_dp) union all ( select '00103673' as scdw_code, '鲁西电厂' as scdw_name, '机组1'as jzmc, last(jz1fdjyggl) as fdgl, '填报' as jzzt, last(ts) as ts from ep_iot.sldc_dp) union all ( select '00103673' as scdw_code, '鲁西电厂' as scdw_name, '机组2'as jzmc, last(jz2fdjyggl) as fdgl, '填报' as jzzt, last(ts) as ts from ep_iot.sldc_dp) union all ( select '01061584' as scdw_code, '富源热电' as scdw_name, '机组1'as jzmc, last(jz1fdjyggl) as fdgl, '填报' as jzzt ,last(ts) as ts from ep_iot.sldc_dp) union all ( select '01061584' as scdw_code, '富源热电' as scdw_name, '机组2'as jzmc, last(jz2fdjyggl) as fdgl, '填报' as jzzt ,last(ts) as ts from ep_iot.sldc_dp)) where scdw_code like '%%';"
+        tdSql.query(sql, queryTimes=1)
+        tdSql.checkCols(6)
+        tdSql.checkRows(6)
+        ##tdSql.execute("drop database ep_iot")
 
     def run(self):
         tdSql.prepare()