diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/stats/JoinEstimation.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/stats/JoinEstimation.java
index f5fd89a6d5..8531321e3f 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/stats/JoinEstimation.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/stats/JoinEstimation.java
@@ -26,6 +26,7 @@ import org.apache.doris.nereids.trees.plans.algebra.Join;
 import org.apache.doris.statistics.ColumnStatistic;
 import org.apache.doris.statistics.StatsDeriveResult;
 
+import com.google.common.base.Preconditions;
 import com.google.common.collect.Maps;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -37,7 +38,21 @@ import org.apache.logging.log4j.Logger;
 public class JoinEstimation {
     private static final Logger LOG = LogManager.getLogger(JoinEstimation.class);
 
-    private static double estimateInnerJoin(Join join, EqualTo equalto,
+    private static double estimateInnerJoin(StatsDeriveResult leftStats, StatsDeriveResult rightStats, Join join) {
+        Preconditions.checkArgument(join.getJoinType() == JoinType.INNER_JOIN);
+        double rowCount = Double.MAX_VALUE;
+        if (join.getHashJoinConjuncts().isEmpty()) {
+            rowCount = leftStats.getRowCount() * rightStats.getRowCount();
+        } else {
+            for (Expression equalTo : join.getHashJoinConjuncts()) {
+                double tmpRowCount = estimateEqualJoinCondition((EqualTo) equalTo, leftStats, rightStats);
+                rowCount = Math.min(rowCount, tmpRowCount);
+            }
+        }
+        return rowCount;
+    }
+
+    private static double estimateEqualJoinCondition(EqualTo equalto,
             StatsDeriveResult leftStats, StatsDeriveResult rightStats) {
         SlotReference eqRight = (SlotReference) equalto.child(1).getInputSlots().toArray()[0];
 
@@ -72,6 +87,11 @@ public class JoinEstimation {
         return leftCount - leftCount / Math.max(2, rightCount);
     }
 
+    private static double estimateFullOuterJoin(StatsDeriveResult leftStats, StatsDeriveResult rightStats, Join join) {
+        //TODO: after we have histogram, re-design this logical
+        return leftStats.getRowCount() + rightStats.getRowCount();
+    }
+
     /**
      * estimate join
      */
@@ -95,15 +115,7 @@ public class JoinEstimation {
                 rowCount = estimateLeftSemiJoin(rightCount, leftCount);
             }
         } else if (joinType == JoinType.INNER_JOIN) {
-            if (join.getHashJoinConjuncts().isEmpty()) {
-                rowCount = leftStats.getRowCount() * rightStats.getRowCount();
-            } else {
-                for (Expression joinConjunct : join.getHashJoinConjuncts()) {
-                    double tmpRowCount = estimateInnerJoin(join,
-                            (EqualTo) joinConjunct, leftStats, rightStats);
-                    rowCount = Math.min(rowCount, tmpRowCount);
-                }
-            }
+            rowCount = estimateInnerJoin(leftStats, rightStats, join);
         } else if (joinType == JoinType.LEFT_OUTER_JOIN) {
             rowCount = leftStats.getRowCount();
         } else if (joinType == JoinType.RIGHT_OUTER_JOIN) {
@@ -111,6 +123,8 @@ public class JoinEstimation {
         } else if (joinType == JoinType.CROSS_JOIN) {
             rowCount = CheckedMath.checkedMultiply(leftStats.getRowCount(),
                     rightStats.getRowCount());
+        } else if (joinType == JoinType.FULL_OUTER_JOIN) {
+            rowCount = estimateFullOuterJoin(leftStats, rightStats, join);
         } else {
             LOG.warn("join type is not supported: " + joinType);
             throw new RuntimeException("joinType is not supported");