diff --git a/weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/request/CombineCloseRequest.java b/weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/request/CombineCloseRequest.java
index b397f0f1c0..428878dc77 100644
--- a/weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/request/CombineCloseRequest.java
+++ b/weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/request/CombineCloseRequest.java
@@ -87,5 +87,33 @@ public static class SubOrders implements Serializable {
      */
     @SerializedName(value = "out_trade_no")
     private String outTradeNo;
+    /**
+     * <pre>
+     * 字段名：二级商户号
+     * 变量名：sub_mchid
+     * 是否必填：是
+     * 类型：string[1,32]
+     * 描述：
+     *  二级商户商户号，由微信支付生成并下发。服务商子商户的商户号，被合单方。直连商户不用传二级商户号。
+     *  示例值：1900000109
+     * </pre>
+     */
+    @SerializedName(value = "sub_mchid")
+    private String subMchid;
+    /**
+     * <pre>
+     * 字段名：子商户应用ID
+     * 变量名：sub_appid
+     * 是否必填：是
+     * 类型：string[1,32]
+     * 描述：
+     *  子商户申请的应用ID，全局唯一。请求基础下单接口时请注意APPID的应用属性，例如公众号场景下，
+     *  需使用应用属性为公众号的APPID 若sub_openid有传的情况下，
+     *  sub_appid必填，且sub_appid需与sub_openid对应
+     *  示例值：wxd678efh567hg6999
+     * </pre>
+     */
+    @SerializedName(value = "sub_appid")
+    private String subAppid;
   }
 }
diff --git a/weixin-java-pay/src/test/java/com/github/binarywang/wxpay/bean/request/CombineCloseRequestTest.java b/weixin-java-pay/src/test/java/com/github/binarywang/wxpay/bean/request/CombineCloseRequestTest.java
new file mode 100644
index 0000000000..aaaa693324
--- /dev/null
+++ b/weixin-java-pay/src/test/java/com/github/binarywang/wxpay/bean/request/CombineCloseRequestTest.java
@@ -0,0 +1,47 @@
+package com.github.binarywang.wxpay.bean.request;
+
+import com.google.gson.Gson;
+import org.testng.annotations.Test;
+
+import java.util.Arrays;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author <a href="https://github.com/binarywang">Binary Wang</a>
+ * created on  2024-12-19
+ */
+public class CombineCloseRequestTest {
+
+  @Test
+  public void testSerialization() {
+    CombineCloseRequest request = new CombineCloseRequest();
+    request.setCombineAppid("wxd678efh567hg6787");
+    request.setCombineOutTradeNo("P20150806125346");
+
+    CombineCloseRequest.SubOrders subOrder = new CombineCloseRequest.SubOrders();
+    subOrder.setMchid("1900000109");
+    subOrder.setOutTradeNo("20150806125346");
+    subOrder.setSubMchid("1230000109");
+    subOrder.setSubAppid("wxd678efh567hg6999");
+
+    request.setSubOrders(Arrays.asList(subOrder));
+
+    Gson gson = new Gson();
+    String json = gson.toJson(request);
+
+    // Verify that the JSON contains the new fields
+    assertThat(json).contains("\"sub_mchid\":\"1230000109\"");
+    assertThat(json).contains("\"sub_appid\":\"wxd678efh567hg6999\"");
+    assertThat(json).contains("\"combine_appid\":\"wxd678efh567hg6787\"");
+    assertThat(json).contains("\"mchid\":\"1900000109\"");
+    assertThat(json).contains("\"out_trade_no\":\"20150806125346\"");
+
+    // Verify deserialization works
+    CombineCloseRequest deserializedRequest = gson.fromJson(json, CombineCloseRequest.class);
+    assertThat(deserializedRequest.getCombineAppid()).isEqualTo("wxd678efh567hg6787");
+    assertThat(deserializedRequest.getSubOrders()).hasSize(1);
+    assertThat(deserializedRequest.getSubOrders().get(0).getSubMchid()).isEqualTo("1230000109");
+    assertThat(deserializedRequest.getSubOrders().get(0).getSubAppid()).isEqualTo("wxd678efh567hg6999");
+  }
+}
\ No newline at end of file