diff --git a/src/main/java/com/actiontech/dble/plan/common/item/Item.java b/src/main/java/com/actiontech/dble/plan/common/item/Item.java
index 07b370408..733831124 100644
--- a/src/main/java/com/actiontech/dble/plan/common/item/Item.java
+++ b/src/main/java/com/actiontech/dble/plan/common/item/Item.java
@@ -13,6 +13,7 @@ import com.actiontech.dble.plan.common.context.ReferContext;
 import com.actiontech.dble.plan.common.field.Field;
 import com.actiontech.dble.plan.common.field.FieldUtil;
 import com.actiontech.dble.plan.common.field.TypeConversionStatus;
+import com.actiontech.dble.plan.common.item.function.operator.controlfunc.ItemFuncCase;
 import com.actiontech.dble.plan.common.time.*;
 import com.actiontech.dble.plan.node.PlanNode;
 import com.alibaba.druid.sql.ast.SQLExpr;
@@ -1019,7 +1020,7 @@ public abstract class Item {
 
     public final Item reStruct(List<Item> calArgs, boolean isPushDown, List<Field> fields) {
         Item clone = cloneStruct(true, calArgs, isPushDown, fields);
-        if (calArgs.size() > 0) {
+        if (calArgs.size() > 0 && !(clone instanceof ItemFuncCase)) {
             clone.setCharsetIndex(calArgs.get(0).getCharsetIndex());
         }
         return clone;
diff --git a/src/main/java/com/actiontech/dble/plan/common/item/function/operator/controlfunc/ItemFuncCase.java b/src/main/java/com/actiontech/dble/plan/common/item/function/operator/controlfunc/ItemFuncCase.java
index 186c1dbff..c1480dabd 100644
--- a/src/main/java/com/actiontech/dble/plan/common/item/function/operator/controlfunc/ItemFuncCase.java
+++ b/src/main/java/com/actiontech/dble/plan/common/item/function/operator/controlfunc/ItemFuncCase.java
@@ -33,12 +33,13 @@ public class ItemFuncCase extends ItemFunc {
      * @param firstExprNum -1 means no case exp,else means the index of args in case exp,case and else exp are at the end of args
      * @param elseExprNum  the index of else in args
      */
-    public ItemFuncCase(List<Item> args, int ncases, int firstExprNum, int elseExprNum) {
+    public ItemFuncCase(List<Item> args, int ncases, int firstExprNum, int elseExprNum, int charsetIndex) {
         super(args);
         this.ncases = ncases;
         this.firstExprNum = firstExprNum;
         this.elseExprNum = elseExprNum;
         this.cachedResultType = ItemResult.INT_RESULT;
+        this.charsetIndex = charsetIndex;
     }
 
     @Override
@@ -227,6 +228,6 @@ public class ItemFuncCase extends ItemFunc {
             newArgs = cloneStructList(args);
         else
             newArgs = calArgs;
-        return new ItemFuncCase(newArgs, ncases, firstExprNum, elseExprNum);
+        return new ItemFuncCase(newArgs, ncases, firstExprNum, elseExprNum, charsetIndex);
     }
 }
diff --git a/src/main/java/com/actiontech/dble/plan/visitor/MySQLItemVisitor.java b/src/main/java/com/actiontech/dble/plan/visitor/MySQLItemVisitor.java
index 8fc425e7f..2e7ded842 100644
--- a/src/main/java/com/actiontech/dble/plan/visitor/MySQLItemVisitor.java
+++ b/src/main/java/com/actiontech/dble/plan/visitor/MySQLItemVisitor.java
@@ -396,7 +396,7 @@ public class MySQLItemVisitor extends MySqlASTVisitorAdapter {
             elseExprNum = args.size();
             args.add(getItem(elseExpr));
         }
-        item = new ItemFuncCase(args, nCases, firstExprNum, elseExprNum);
+        item = new ItemFuncCase(args, nCases, firstExprNum, elseExprNum, this.charsetIndex);
     }
 
     @Override