diff --git a/src/client/src/tscStream.c b/src/client/src/tscStream.c
index 88c72a91a6ab7a3b6b0a741dcfb2215662c63326..1296caf7600d6ce9417981cfc2b401c641d04d05 100644
--- a/src/client/src/tscStream.c
+++ b/src/client/src/tscStream.c
@@ -30,6 +30,7 @@ static void tscProcessStreamQueryCallback(void *param, TAOS_RES *tres, int numOf
 static void tscProcessStreamRetrieveResult(void *param, TAOS_RES *res, int numOfRows);
 static void tscSetNextLaunchTimer(SSqlStream *pStream, SSqlObj *pSql);
 static void tscSetRetryTimer(SSqlStream *pStream, SSqlObj *pSql, int64_t timer);
+static int64_t getLaunchTimeDelay(const SSqlStream* pStream);
 
 static int64_t getDelayValueAfterTimewindowClosed(SSqlStream* pStream, int64_t launchDelay) {
   return taosGetTimestamp(pStream->precision) + launchDelay - pStream->stime - 1;
@@ -178,13 +179,30 @@ static void tscProcessStreamTimer(void *handle, void *tmrId) {
       if (pStream->interval.intervalUnit == 'y' || pStream->interval.intervalUnit == 'n') {
         timer = 86400 * 1000l;
       } else {
-        timer = convertTimePrecision(timer, pStream->precision, TSDB_TIME_PRECISION_MILLI);
+        int64_t next_time = 0; 
+        while(1) {
+          // get next time
+          next_time = taosTimeAdd(pStream->stime, pStream->interval.sliding, pStream->interval.intervalUnit, TSDB_TIME_PRECISION_MILLI);
+          next_time = taosTimeTruncate(next_time, &pStream->interval, pStream->precision);
+          timer = next_time - taosGetTimestamp(pStream->precision); // next time - now()
+          if(timer < 0 ) {
+            tscDebug("CQ next time < now so loop add sliding. next_time=%" PRId64, next_time);
+            continue;
+          }
+
+          // calc launch delay time
+          int64_t delay = getLaunchTimeDelay((const SSqlStream*)pStream);
+          timer += delay;
+          tscDebug("CQ execute next query after %" PRId64 "ms (delay=%" PRId64 ")", timer, delay);
+          break;
+        }  
       }
       tscSetRetryTimer(pStream, pSql, timer);
       return;
     }
   }
 
+  tscDebug("CQ ProcessStreamTimer skey=%" PRId64 " ekey=%" PRId64 " stime=%" PRId64 " endtime=%" PRId64, pQueryInfo->window.skey, pQueryInfo->window.ekey, pStream->stime, pStream->etime);
   // launch stream computing in a new thread
   SSchedMsg schedMsg = { 0 };
   schedMsg.fp = tscProcessStreamLaunchQuery;
@@ -195,7 +213,7 @@ static void tscProcessStreamTimer(void *handle, void *tmrId) {
 }
 
 static void tscProcessStreamQueryCallback(void *param, TAOS_RES *tres, int numOfRows) {
-  SSqlStream *pStream = (SSqlStream *)param;
+  SSqlStream *pStream = (SSqlStream *)param; 
   if (tres == NULL || numOfRows < 0) {
     int64_t retryDelay = tscGetRetryDelayTime(pStream, pStream->interval.sliding, pStream->precision);
     tscError("0x%"PRIx64" stream:%p, query data failed, code:0x%08x, retry in %" PRId64 "ms", pStream->pSql->self,
@@ -216,7 +234,6 @@ static void tscProcessStreamQueryCallback(void *param, TAOS_RES *tres, int numOf
     pStream->pSql->subState.numOfSub = 0;
 
     pTableMetaInfo->vgroupList = tscVgroupInfoClear(pTableMetaInfo->vgroupList);
-
     tscSetRetryTimer(pStream, pStream->pSql, retryDelay);
     return;
   }
@@ -479,7 +496,6 @@ static void tscProcessStreamRetrieveResult(void *param, TAOS_RES *res, int numOf
   if (pSql == NULL || numOfRows < 0) {
     int64_t retryDelayTime = tscGetRetryDelayTime(pStream, pStream->interval.sliding, pStream->precision);
     tscError("stream:%p, retrieve data failed, code:0x%08x, retry in %" PRId64 " ms", pStream, numOfRows, retryDelayTime);
-  
     tscSetRetryTimer(pStream, pStream->pSql, retryDelayTime);
     return;
   }
@@ -552,7 +568,6 @@ static void tscProcessStreamRetrieveResult(void *param, TAOS_RES *res, int numOf
         // todo set retry dynamic time
         int32_t retry = tsProjectExecInterval;
         tscError("0x%"PRIx64" stream:%p, retrieve no data, code:0x%08x, retry in %" PRId32 "ms", pSql->self, pStream, numOfRows, retry);
-
         tscSetRetryTimer(pStream, pStream->pSql, retry);
         return;
       }
@@ -617,28 +632,33 @@ static void tscSetRetryTimer(SSqlStream *pStream, SSqlObj *pSql, int64_t timer)
   taosTmrReset(tscProcessStreamTimer, (int32_t)timer, pStream, tscTmr, &pStream->pTimer);
 }
 
+// get need delay time for every launch to exeucte query, include first and next launch 
 static int64_t getLaunchTimeDelay(const SSqlStream* pStream) {
+  // step 1 read setting delay time in taos.cfg
   int64_t maxDelay = convertTimePrecision(tsMaxStreamComputDelay, TSDB_TIME_PRECISION_MILLI, pStream->precision);
-
-  int64_t delayDelta = maxDelay;
+  int64_t ratioDelay = maxDelay;
   if (pStream->interval.intervalUnit != 'n' && pStream->interval.intervalUnit != 'y') {
-    delayDelta = (int64_t)(pStream->interval.sliding * tsStreamComputDelayRatio);
-    if (delayDelta > maxDelay) {
-      delayDelta = maxDelay;
+    ratioDelay= (int64_t)(pStream->interval.sliding * tsStreamComputDelayRatio);
+    if (ratioDelay > maxDelay) {
+      ratioDelay = maxDelay;
     }
-    int64_t remainTimeWindow = pStream->interval.sliding - delayDelta;
+    int64_t remainTimeWindow = pStream->interval.sliding - ratioDelay;
     if (maxDelay > remainTimeWindow) {
       maxDelay = (int64_t)(remainTimeWindow / 1.5f);
     }
   }
   
-  int64_t currentDelay = (rand() % maxDelay);  // a random number
-  currentDelay += delayDelta;
+  // PART 2 calc allDelay = rand delay + fixed delay
+  int64_t allDelay = (rand() % maxDelay) + ratioDelay;
   if (pStream->interval.intervalUnit != 'n' && pStream->interval.intervalUnit != 'y') {
-    assert(currentDelay < pStream->interval.sliding);
+    if(allDelay >= pStream->interval.sliding) {
+      tscWarn("CQ delay >= sliding error. delay=%" PRId64 " sliding=%" PRId64 ". so set delay=sliding/2.", allDelay, pStream->interval.sliding);
+      allDelay = pStream->interval.sliding / 2;
+    }
   }
-  
-  return currentDelay;
+
+  tscDebug("getLanchDelay allDelay=%" PRId64 "(ratioDelay=%" PRId64 ")", allDelay, ratioDelay);
+  return allDelay;
 }
 
 
@@ -687,7 +707,6 @@ static void tscSetNextLaunchTimer(SSqlStream *pStream, SSqlObj *pSql) {
   timer += getLaunchTimeDelay(pStream);
   
   timer = convertTimePrecision(timer, pStream->precision, TSDB_TIME_PRECISION_MILLI);
-
   tscSetRetryTimer(pStream, pSql, timer);
 }
 
@@ -779,16 +798,18 @@ static int64_t tscGetStreamStartTimestamp(SSqlObj *pSql, SSqlStream *pStream, in
   return stime;
 }
 
-static int64_t tscGetLaunchTimestamp(const SSqlStream *pStream) {
+static int64_t tscGetFirstLaunchTime(const SSqlStream *pStream) {
+  // PART 1 now to stime span
   int64_t timer = 0, now = taosGetTimestamp(pStream->precision);
   if (pStream->stime > now) {
     timer = pStream->stime - now;
   }
 
-  int64_t startDelay = convertTimePrecision(tsStreamCompStartDelay, TSDB_TIME_PRECISION_MILLI, pStream->precision);
+  // PART 2 stream first Launch need delay, setting with taos.cfg 
+  timer += convertTimePrecision(tsFirstLaunchDelay, TSDB_TIME_PRECISION_MILLI, pStream->precision);
 
+  // PART 3 every launch need delay, include first and next launch 
   timer += getLaunchTimeDelay(pStream);
-  timer += startDelay;
   
   return convertTimePrecision(timer, pStream->precision, TSDB_TIME_PRECISION_MILLI);
 }
@@ -834,7 +855,7 @@ static void tscCreateStream(void *param, TAOS_RES *res, int code) {
     pStream->stime = pStream->ltime;
   }
 
-  int64_t starttime = tscGetLaunchTimestamp(pStream);
+  int64_t starttime = tscGetFirstLaunchTime(pStream);
   pCmd->command = TSDB_SQL_SELECT;
 
   tscAddIntoStreamList(pStream);
diff --git a/src/common/inc/tglobal.h b/src/common/inc/tglobal.h
index 9775a3898fb759873ffe48673062dd8402873041..a0a4b57f8509ca4461d9c7fb91ecd35db6c41e05 100644
--- a/src/common/inc/tglobal.h
+++ b/src/common/inc/tglobal.h
@@ -78,7 +78,7 @@ extern int32_t tsMaxNumOfOrderedResults;
 extern int32_t tsMinSlidingTime;
 extern int32_t tsMinIntervalTime;
 extern int32_t tsMaxStreamComputDelay;
-extern int32_t tsStreamCompStartDelay;
+extern int32_t tsFirstLaunchDelay;
 extern int32_t tsRetryStreamCompDelay;
 extern float   tsStreamComputDelayRatio;  // the delayed computing ration of the whole time window
 extern int32_t tsProjectExecInterval;
diff --git a/src/common/src/tglobal.c b/src/common/src/tglobal.c
index ce942b60c6c91aa6f0e3773833359ada939c3d16..7a270bb368ae1be7a0aae9ca8d869ac0b09a21ab 100644
--- a/src/common/src/tglobal.c
+++ b/src/common/src/tglobal.c
@@ -98,8 +98,8 @@ int32_t tsMinIntervalTime = 1;
 // 20sec, the maximum value of stream computing delay, changed accordingly
 int32_t tsMaxStreamComputDelay = 20000;
 
-// 10sec, the first stream computing delay time after system launched successfully, changed accordingly
-int32_t tsStreamCompStartDelay = 10000;
+// 10sec, the stream first launched to execute delay time after system launched successfully, changed accordingly
+int32_t tsFirstLaunchDelay = 10000;
 
 // the stream computing delay time after executing failed, change accordingly
 int32_t tsRetryStreamCompDelay = 10 * 1000;
@@ -739,7 +739,7 @@ static void doInitGlobalConfig(void) {
   taosInitConfigOption(cfg);
 
   cfg.option = "maxFirstStreamCompDelay";
-  cfg.ptr = &tsStreamCompStartDelay;
+  cfg.ptr = &tsFirstLaunchDelay; // stream first launch delay time
   cfg.valType = TAOS_CFG_VTYPE_INT32;
   cfg.cfgType = TSDB_CFG_CTYPE_B_CONFIG | TSDB_CFG_CTYPE_B_SHOW;
   cfg.minValue = 1000;