diff --git a/fe/fe-core/src/main/java/org/apache/doris/system/SystemInfoService.java b/fe/fe-core/src/main/java/org/apache/doris/system/SystemInfoService.java
index aa2bcbb34bc0e9..f1c5b0442f4585 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/system/SystemInfoService.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/system/SystemInfoService.java
@@ -1071,7 +1071,7 @@ private long getClusterAvailableCapacityB(String clusterName) {
             if (backend.isDecommissioned()) {
                 // Data on decommissioned backend will move to other backends,
                 // So we need to minus size of those data.
-                capacity -= backend.getTotalCapacityB() - backend.getAvailableCapacityB();
+                capacity -= backend.getDataUsedCapacityB();
             } else {
                 capacity += backend.getAvailableCapacityB();
             }