diff --git a/sentinel-cluster/sentinel-cluster-server-default/src/main/java/com/alibaba/csp/sentinel/cluster/flow/statistic/metric/ClusterMetric.java b/sentinel-cluster/sentinel-cluster-server-default/src/main/java/com/alibaba/csp/sentinel/cluster/flow/statistic/metric/ClusterMetric.java
index 1dbdae21bc..cfe6303e2d 100644
--- a/sentinel-cluster/sentinel-cluster-server-default/src/main/java/com/alibaba/csp/sentinel/cluster/flow/statistic/metric/ClusterMetric.java
+++ b/sentinel-cluster/sentinel-cluster-server-default/src/main/java/com/alibaba/csp/sentinel/cluster/flow/statistic/metric/ClusterMetric.java
@@ -83,7 +83,7 @@ public int tryOccupyNext(ClusterFlowEvent event, int acquireCount, double thresh
         }
         metric.addOccupyPass(acquireCount);
         add(ClusterFlowEvent.WAITING, acquireCount);
-        return 1000 / metric.getSampleCount();
+        return metric.getWindowLengthInMs();
     }
 
     private boolean canOccupy(ClusterFlowEvent event, int acquireCount, double latestQps, double threshold) {
diff --git a/sentinel-cluster/sentinel-cluster-server-default/src/test/java/com/alibaba/csp/sentinel/cluster/flow/statistic/metric/ClusterMetricTest.java b/sentinel-cluster/sentinel-cluster-server-default/src/test/java/com/alibaba/csp/sentinel/cluster/flow/statistic/metric/ClusterMetricTest.java
index b7891767f8..7d2aebd62f 100644
--- a/sentinel-cluster/sentinel-cluster-server-default/src/test/java/com/alibaba/csp/sentinel/cluster/flow/statistic/metric/ClusterMetricTest.java
+++ b/sentinel-cluster/sentinel-cluster-server-default/src/test/java/com/alibaba/csp/sentinel/cluster/flow/statistic/metric/ClusterMetricTest.java
@@ -36,11 +36,11 @@ public void testTryOccupyNext() {
             Assert.assertEquals(4, metric.getSum(ClusterFlowEvent.PASS));
             Assert.assertEquals(1, metric.getSum(ClusterFlowEvent.BLOCK));
             Assert.assertEquals(160, metric.getAvg(ClusterFlowEvent.PASS), 0.01);
-            Assert.assertEquals(200, metric.tryOccupyNext(ClusterFlowEvent.PASS, 111, 900));
+            Assert.assertEquals(5, metric.tryOccupyNext(ClusterFlowEvent.PASS, 111, 900));
             metric.add(ClusterFlowEvent.PASS, 1);
             metric.add(ClusterFlowEvent.PASS, 2);
             metric.add(ClusterFlowEvent.PASS, 1);
-            Assert.assertEquals(200, metric.tryOccupyNext(ClusterFlowEvent.PASS, 222, 900));
+            Assert.assertEquals(5, metric.tryOccupyNext(ClusterFlowEvent.PASS, 222, 900));
             metric.add(ClusterFlowEvent.PASS, 1);
             metric.add(ClusterFlowEvent.PASS, 2);
             metric.add(ClusterFlowEvent.PASS, 1);
diff --git a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/statistic/base/LeapArray.java b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/statistic/base/LeapArray.java
index e67b40e99a..4a8563ff3e 100755
--- a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/statistic/base/LeapArray.java
+++ b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/statistic/base/LeapArray.java
@@ -380,6 +380,14 @@ public int getSampleCount() {
         return sampleCount;
     }
 
+    /**
+     * Get window length of a single bucket in milliseconds.
+     * @return window length in milliseconds
+     */
+    public int getWindowLengthInMs() {
+        return windowLengthInMs;
+    }
+
     /**
      * Get total interval length of the sliding window in milliseconds.
      *