diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/processor/post/RuntimeFilterGenerator.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/processor/post/RuntimeFilterGenerator.java
index e4ee9d9217..776aa5396f 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/processor/post/RuntimeFilterGenerator.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/processor/post/RuntimeFilterGenerator.java
@@ -345,7 +345,8 @@ public class RuntimeFilterGenerator extends PlanPostProcessor {
         }
         ExpressionEstimation estimator = new ExpressionEstimation();
         ColumnStatistic buildColStats = compare.right().accept(estimator, right.getStats());
-        return buildColStats.isUnKnown ? -1 : Math.max(1, (long) buildColStats.ndv);
+        return buildColStats.isUnKnown
+                ? Math.max(1, (long) right.getStats().getRowCount()) : Math.max(1, (long) buildColStats.ndv);
     }
 
     public static Slot checkTargetChild(Expression leftChild) {