diff --git a/source/libs/executor/src/filloperator.c b/source/libs/executor/src/filloperator.c
index 73222ee3756fdc31c3da675ea52de53e10c9db03..6d4b8570d17e0d49a060e9a7180459e3c61be603 100644
--- a/source/libs/executor/src/filloperator.c
+++ b/source/libs/executor/src/filloperator.c
@@ -258,7 +258,7 @@ static int32_t initFillInfo(SFillOperatorInfo* pInfo, SExprInfo* pExpr, int32_t
   STimeWindow w = {0};
   int64_t     startKey = (order == TSDB_ORDER_ASC) ? win.skey : win.ekey;
 
-  getInitialStartTimeWindow(pInterval, startKey, &w, order);
+  getInitialStartTimeWindow(pInterval, startKey, &w, order == TSDB_ORDER_ASC);
   pInfo->pFillInfo = taosCreateFillInfo(w.skey, numOfCols, numOfNotFillCols, capacity, pInterval, fillType, pColInfo,
                                         pInfo->primaryTsCol, order, id);
 
diff --git a/source/libs/executor/src/tfill.c b/source/libs/executor/src/tfill.c
index c98746c241b63c036e3a37b352d6523a0efe4530..a39521f25c8d8bd64c18d89190f168ed72fec4e0 100644
--- a/source/libs/executor/src/tfill.c
+++ b/source/libs/executor/src/tfill.c
@@ -561,7 +561,7 @@ int64_t getNumOfResultsAfterFillGap(SFillInfo* pFillInfo, TSKEY ekey, int32_t ma
     ASSERT(numOfRes >= numOfRows);
   } else {  // reach the end of data
     if ((ekey1 < pFillInfo->currentKey && FILL_IS_ASC_FILL(pFillInfo)) ||
-        (ekey1 >= pFillInfo->currentKey && !FILL_IS_ASC_FILL(pFillInfo))) {
+        (ekey1 > pFillInfo->currentKey && !FILL_IS_ASC_FILL(pFillInfo))) {
       return 0;
     }
     numOfRes = taosTimeCountInterval(ekey1, pFillInfo->currentKey, pFillInfo->interval.sliding,
diff --git a/tests/script/tsim/query/interval.sim b/tests/script/tsim/query/interval.sim
index 833da4a8ba2b3daf495167f06c99d222564a6bf3..e2b0d219cb0eaaace3e571d31a19fa329364c575 100644
--- a/tests/script/tsim/query/interval.sim
+++ b/tests/script/tsim/query/interval.sim
@@ -170,6 +170,42 @@ endi
 #  return -1
 #endi
 
+print ================ step10
+print -------- create database and table
+sql create database if not exists test
+sql use test
+sql create stable st (ts timestamp, c2 int) tags(tg int)
+print -------- insert 300 rows data
+$i = 0
+while $i < 300
+  $t = 1577807983000
+  $cc = $i * 1000
+  $t = $t + $cc
+  sql select $i % 3
+  if $data00 != 0.000000000 then
+    goto continue_while
+  endi
+  sql select $i % 4
+  if $data00 == 0.000000000 then
+    goto continue_while
+  endi
+  sql insert into t1 using st tags(1) values ( $t , $i )
+  continue_while:
+    $i = $i + 1
+endw
+
+$ms1 = 1577808120000
+$ms2 = 1577808000000
+sql select * from (select _wstart, last(ts) as ts, avg(c2) as av from t1 where ts <= $ms1 and ts >= $ms2 interval(10s) sliding(1s) fill(NULL)) order by ts asc
+print ----> select asc rows: $rows
+$asc_rows = $rows
+sql select * from (select _wstart, last(ts) as ts, avg(c2) as av from t1 where ts <= $ms1 and ts >= $ms2 interval(10s) sliding(1s) fill(NULL)) order by ts desc
+print ----> select desc rows: $rows
+$desc_rows = $rows
+if $desc_rows != $asc_rows then
+  return -1
+endi
+
 print =============== clear
 #sql drop database $db
 #sql select * from information_schema.ins_databases