diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/exploration/mv/PartitionCompensator.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/exploration/mv/PartitionCompensator.java
index 0ee88ce82af070..ecb3c1d6cbba85 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/exploration/mv/PartitionCompensator.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/exploration/mv/PartitionCompensator.java
@@ -85,8 +85,10 @@ public static Pair<Map<BaseTableInfo, Set<String>>, Map<BaseTableInfo, Set<Strin
         }
         MTMVPartitionInfo mvCustomPartitionInfo = mtmv.getMvPartitionInfo();
         BaseTableInfo relatedPartitionTable = mvCustomPartitionInfo.getRelatedTableInfo();
-        if (relatedPartitionTable == null || queryUsedBaseTablePartitionNameSet.isEmpty()) {
+        if (relatedPartitionTable == null || queryUsedBaseTablePartitionNameSet.isEmpty()
+                || !relatedPartitionTable.isInternalTable()) {
             // if mv is not partitioned or query not query any partition, doesn't compensate
+            // in 2.1, external table should not compensate union all
             return Pair.of(ImmutableMap.of(), ImmutableMap.of());
         }
         Collection<Partition> mvValidPartitions = cascadesContext.getStatementContext()