diff --git a/src/sql/engine/aggregate/ob_aggregate_processor.cpp b/src/sql/engine/aggregate/ob_aggregate_processor.cpp
index 90b14e5ca5..2bcee9ef8f 100644
--- a/src/sql/engine/aggregate/ob_aggregate_processor.cpp
+++ b/src/sql/engine/aggregate/ob_aggregate_processor.cpp
@@ -3122,11 +3122,16 @@ int ObAggregateCalcFunc::add_calc(const ObDatum& left_value, const ObDatum& righ
         break;
       }
       case ObNumberTC: {
-        if (left_value.is_null() && OB_FAIL(clone_number_cell(right_value.get_number(), result_datum, out_allocator))) {
-          LOG_WARN("fail to clone number cell", K(ret));
-        } else if (right_value.is_null() &&
-                   OB_FAIL(clone_number_cell(left_value.get_number(), result_datum, out_allocator))) {
-          LOG_WARN("fail to clone number cell", K(ret));
+        if (left_value.is_null()) {
+          if (OB_FAIL(clone_number_cell(right_value.get_number(),
+              result_datum, out_allocator))) {
+            LOG_WARN("fail to clone number cell", K(ret));
+          }
+        } else if (right_value.is_null()) {
+          if (OB_FAIL(clone_number_cell(left_value.get_number(),
+              result_datum, out_allocator))) {
+            LOG_WARN("fail to clone number cell", K(ret));
+          }
         } else {
           char buf_alloc[ObNumber::MAX_CALC_BYTE_LEN];
           ObDataBuffer allocator(buf_alloc, ObNumber::MAX_CALC_BYTE_LEN);
diff --git a/src/sql/engine/window_function/ob_window_function_op.cpp b/src/sql/engine/window_function/ob_window_function_op.cpp
index 3c266853a1..9507828d0a 100644
--- a/src/sql/engine/window_function/ob_window_function_op.cpp
+++ b/src/sql/engine/window_function/ob_window_function_op.cpp
@@ -1364,7 +1364,12 @@ int ObWindowFunctionOp::parallel_winbuf_process()
                 ObDatum& l_datum = new_row->cells()[idx];
                 const ObDatum& r_datum = row->cells()[idx];
                 ObDatumCmpFuncType cmp_func = cmp_funcs.at(cmp_index);
-                if (cmp_func(l_datum, r_datum) < 0) {
+                // null-last cmp func should ignore null in max calc
+                if (r_datum.is_null() && !l_datum.is_null()) {
+                  /*do nothing*/
+                } else if (!r_datum.is_null() && l_datum.is_null()) {
+                  l_datum = r_datum;
+                } else if (cmp_func(l_datum, r_datum) < 0) {
                   l_datum = r_datum;
                 }
                 cmp_index++;
@@ -1374,6 +1379,7 @@ int ObWindowFunctionOp::parallel_winbuf_process()
                 ObDatum& l_datum = new_row->cells()[idx];
                 const ObDatum& r_datum = row->cells()[idx];
                 ObDatumCmpFuncType cmp_func = cmp_funcs.at(cmp_index);
+                // null-last cmp func no need null special calc in min calc
                 if (cmp_func(l_datum, r_datum) > 0) {
                   l_datum = r_datum;
                 }