diff --git a/sky-server/src/main/java/com/sky/controller/user/ShoppingCartController.java b/sky-server/src/main/java/com/sky/controller/user/ShoppingCartController.java
index 8c1caad..108c69d 100644
--- a/sky-server/src/main/java/com/sky/controller/user/ShoppingCartController.java
+++ b/sky-server/src/main/java/com/sky/controller/user/ShoppingCartController.java
@@ -48,6 +48,10 @@ public class ShoppingCartController {
         return Result.success(list);
     }
 
+    /**
+     * clean shopping cart
+     * @return
+     */
     @DeleteMapping("/clean")
     @ApiOperation("clean the shopping cart")
     public Result clean(){
@@ -55,4 +59,16 @@ public class ShoppingCartController {
         shoppingCartService.cleanShoppingCart();
         return Result.success();
     }
+
+    /**
+     * subtract an item from the shopping cart
+     * @param shoppingCartDTO
+     * @return
+     */
+    @PostMapping("/sub")
+    @ApiOperation("subtract an item from the shopping cart")
+    public Result sub(@RequestBody ShoppingCartDTO shoppingCartDTO){
+        shoppingCartService.subtractFromShoppingCart(shoppingCartDTO);
+        return Result.success();
+    }
 }
diff --git a/sky-server/src/main/java/com/sky/mapper/ShoppingCartMapper.java b/sky-server/src/main/java/com/sky/mapper/ShoppingCartMapper.java
index 04b7127..4627cd6 100644
--- a/sky-server/src/main/java/com/sky/mapper/ShoppingCartMapper.java
+++ b/sky-server/src/main/java/com/sky/mapper/ShoppingCartMapper.java
@@ -45,4 +45,10 @@ public interface ShoppingCartMapper {
      */
     @Delete("delete from sky_take_out.shopping_cart where user_id = #{userId}")
     void clean(Long userId);
+
+    /**
+     * delete the item that number is 0 from the shopping cart
+     * @param shoppingCart
+     */
+    void delete(ShoppingCart shoppingCart);
 }
diff --git a/sky-server/src/main/java/com/sky/service/ShoppingCartService.java b/sky-server/src/main/java/com/sky/service/ShoppingCartService.java
index c2293b4..cea500d 100644
--- a/sky-server/src/main/java/com/sky/service/ShoppingCartService.java
+++ b/sky-server/src/main/java/com/sky/service/ShoppingCartService.java
@@ -27,4 +27,10 @@ public interface ShoppingCartService {
      * clean shopping cart
      */
     void cleanShoppingCart();
+
+    /**
+     * subtract an item from the shopping cart
+     * @param shoppingCartDTO
+     */
+    void subtractFromShoppingCart(ShoppingCartDTO shoppingCartDTO);
 }
diff --git a/sky-server/src/main/java/com/sky/service/impl/ShoppingCartServiceImpl.java b/sky-server/src/main/java/com/sky/service/impl/ShoppingCartServiceImpl.java
index fb5ab78..17daebd 100644
--- a/sky-server/src/main/java/com/sky/service/impl/ShoppingCartServiceImpl.java
+++ b/sky-server/src/main/java/com/sky/service/impl/ShoppingCartServiceImpl.java
@@ -94,4 +94,28 @@ public class ShoppingCartServiceImpl implements ShoppingCartService {
         Long userId = BaseContext.getCurrentId();
         shoppingCartMapper.clean(userId);
     }
+
+    /**
+     * subtract an item from the shopping cart
+     * @param shoppingCartDTO
+     */
+    @Override
+    public void subtractFromShoppingCart(ShoppingCartDTO shoppingCartDTO) {
+        //construct an object that contains the basic properties : userId, set meal/dish id, dish flavor
+        ShoppingCart shoppingCart = new ShoppingCart();
+        BeanUtils.copyProperties(shoppingCartDTO, shoppingCart);
+        shoppingCart.setUserId(BaseContext.getCurrentId());
+
+        List<ShoppingCart> list = shoppingCartMapper.list(shoppingCart);
+        if (!list.isEmpty()) {
+            shoppingCart = list.get(0);
+            //check the number of shopping cart
+            if (shoppingCart.getNumber() > 1) {
+                shoppingCart.setNumber(shoppingCart.getNumber() - 1);
+                shoppingCartMapper.updateNumberById(shoppingCart);
+            } else {
+                shoppingCartMapper.delete(shoppingCart);
+            }
+        }
+    }
 }
diff --git a/sky-server/src/main/resources/mapper/ShoppingCartMapper.xml b/sky-server/src/main/resources/mapper/ShoppingCartMapper.xml
index 43881ff..b63d361 100644
--- a/sky-server/src/main/resources/mapper/ShoppingCartMapper.xml
+++ b/sky-server/src/main/resources/mapper/ShoppingCartMapper.xml
@@ -3,6 +3,23 @@
         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 <mapper namespace="com.sky.mapper.ShoppingCartMapper">
+    <delete id="delete">
+        delete from sky_take_out.shopping_cart
+        <where>
+            <if test="userId != null">
+                and user_id = #{userId}
+            </if>
+            <if test="setmealId != null">
+                and setmeal_id = #{setmealId}
+            </if>
+            <if test="dishId!= null">
+                and dish_id = #{dishId}
+            </if>
+            <if test="dishFlavor != null">
+                and dish_flavor = #{dishFlavor}
+            </if>
+        </where>
+    </delete>
 
     <select id="list" resultType="com.sky.entity.ShoppingCart">
         select * from sky_take_out.shopping_cart