diff --git a/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/query/ServerQuery.java b/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/query/ServerQuery.java
index b269703ad..5651a8d8d 100644
--- a/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/query/ServerQuery.java
+++ b/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/query/ServerQuery.java
@@ -65,9 +65,9 @@ public class ServerQuery implements Query {
     }
 
     public ResponseTimeTrend getServerResponseTimeTrend(int serverId, Duration duration) throws ParseException {
-        long start = DurationUtils.INSTANCE.exchangeToTimeBucket(duration.getStart());
-        long end = DurationUtils.INSTANCE.exchangeToTimeBucket(duration.getEnd());
-        return getServerService().getServerResponseTimeTrend(serverId, duration.getStep(), start, end);
+        long startTimeBucket = DurationUtils.INSTANCE.exchangeToTimeBucket(duration.getStart());
+        long endTimeBucket = DurationUtils.INSTANCE.exchangeToTimeBucket(duration.getEnd());
+        return getServerService().getServerResponseTimeTrend(serverId, duration.getStep(), startTimeBucket, endTimeBucket);
     }
 
     public ThroughputTrend getServerTPSTrend(int serverId, Duration duration) throws ParseException {
diff --git a/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/service/ServerService.java b/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/service/ServerService.java
index 41620c751..10f02715f 100644
--- a/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/service/ServerService.java
+++ b/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/service/ServerService.java
@@ -92,10 +92,10 @@ public class ServerService {
         return serverInfos;
     }
 
-    public ResponseTimeTrend getServerResponseTimeTrend(int instanceId, Step step, long start,
-        long end) throws ParseException {
+    public ResponseTimeTrend getServerResponseTimeTrend(int instanceId, Step step, long startTimeBucket,
+        long endTimeBucket) throws ParseException {
         ResponseTimeTrend responseTimeTrend = new ResponseTimeTrend();
-        List<DurationPoint> durationPoints = DurationUtils.INSTANCE.getDurationPoints(step, start, end);
+        List<DurationPoint> durationPoints = DurationUtils.INSTANCE.getDurationPoints(step, startTimeBucket, endTimeBucket);
         List<Integer> trends = instanceMetricUIDAO.getResponseTimeTrend(instanceId, step, durationPoints);
         responseTimeTrend.setTrendList(trends);
         return responseTimeTrend;
diff --git a/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/utils/DurationUtils.java b/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/utils/DurationUtils.java
index d88a23657..52e5976dd 100644
--- a/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/utils/DurationUtils.java
+++ b/apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/utils/DurationUtils.java
@@ -139,11 +139,11 @@ public enum DurationUtils {
         return dateTime;
     }
 
-    public List<DurationPoint> getDurationPoints(Step step, long start, long end) throws ParseException {
-        DateTime dateTime = parseToDateTime(step, start);
+    public List<DurationPoint> getDurationPoints(Step step, long startTimeBucket, long endTimeBucket) throws ParseException {
+        DateTime dateTime = parseToDateTime(step, startTimeBucket);
 
         List<DurationPoint> durations = new LinkedList<>();
-        durations.add(new DurationPoint(start, secondsBetween(step, dateTime)));
+        durations.add(new DurationPoint(startTimeBucket, secondsBetween(step, dateTime)));
 
         int i = 0;
         do {
@@ -176,10 +176,10 @@ public enum DurationUtils {
             }
             i++;
             if (i > 500) {
-                throw new UnexpectedException("Duration data error, step: " + step.name() + ", start: " + start + ", end: " + end);
+                throw new UnexpectedException("Duration data error, step: " + step.name() + ", start: " + startTimeBucket + ", end: " + endTimeBucket);
             }
         }
-        while (end != durations.get(durations.size() - 1).getPoint());
+        while (endTimeBucket != durations.get(durations.size() - 1).getPoint());
 
         return durations;
     }