diff --git a/weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/notify/WxPayOrderNotifyResult.java b/weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/notify/WxPayOrderNotifyResult.java
index 27e8c1e1e..8f16e5d4e 100644
--- a/weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/notify/WxPayOrderNotifyResult.java
+++ b/weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/notify/WxPayOrderNotifyResult.java
@@ -342,7 +342,9 @@ public class WxPayOrderNotifyResult extends BaseWxPayResult implements Serializa
 
   @Override
   public Map<String, String> toMap() {
-    Map<String, String> resultMap = SignUtils.xmlBean2Map(this);
+    // 使用父类的 toMap() 方法，直接从原始 XML 解析所有字段，
+    // 确保包含未在 Java Bean 中定义的字段，避免签名验证失败
+    Map<String, String> resultMap = super.toMap();
     if (this.getCouponCount() != null && this.getCouponCount() > 0) {
       for (int i = 0; i < this.getCouponCount(); i++) {
         WxPayOrderNotifyCoupon coupon = couponList.get(i);
diff --git a/weixin-java-pay/src/test/java/com/github/binarywang/wxpay/bean/notify/WxPayOrderNotifyUnknownFieldTest.java b/weixin-java-pay/src/test/java/com/github/binarywang/wxpay/bean/notify/WxPayOrderNotifyUnknownFieldTest.java
new file mode 100644
index 000000000..be35523ec
--- /dev/null
+++ b/weixin-java-pay/src/test/java/com/github/binarywang/wxpay/bean/notify/WxPayOrderNotifyUnknownFieldTest.java
@@ -0,0 +1,104 @@
+package com.github.binarywang.wxpay.bean.notify;
+
+import com.github.binarywang.wxpay.constant.WxPayConstants;
+import org.apache.commons.codec.digest.DigestUtils;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+import java.util.*;
+
+/**
+ * 测试当微信支付回调 XML 包含未在 Java Bean 中定义的字段时，签名验证是否正常。
+ * <p>
+ * 问题背景：当微信返回的 XML 包含某些未在 WxPayOrderNotifyResult 中定义的字段时，
+ * 这些字段会被微信服务器用于签名计算。如果 toMap() 方法丢失了这些字段，
+ * 则签名验证会失败，抛出 "参数格式校验错误！" 异常。
+ * </p>
+ * <p>
+ * 解决方案：修改 WxPayOrderNotifyResult.toMap() 方法，使用父类的 toMap() 方法
+ * 直接从原始 XML 解析所有字段，而不是使用 SignUtils.xmlBean2Map(this)。
+ * </p>
+ *
+ * @see <a href="https://github.com/binarywang/WxJava/issues/3750">Issue #3750</a>
+ */
+public class WxPayOrderNotifyUnknownFieldTest {
+
+  private static final String MCH_KEY = "testmchkey1234567890123456789012";
+  private static final List<String> NO_SIGN_PARAMS = Arrays.asList("sign", "key", "xmlString", "xmlDoc", "couponList");
+
+  @Test
+  public void testSignatureWithUnknownField() throws Exception {
+    // 创建一个测试用的 XML，包含一个未知字段 (未在 WxPayOrderNotifyResult 中定义)
+    Map<String, String> params = new LinkedHashMap<>();
+    params.put("appid", "wx58ff40508696691f");
+    params.put("bank_type", "ICBC_DEBIT");
+    params.put("cash_fee", "1");
+    params.put("fee_type", "CNY");
+    params.put("is_subscribe", "N");
+    params.put("mch_id", "1545462911");
+    params.put("nonce_str", "1761723102373");
+    params.put("openid", "o1gdd16CZCi6yYvkn6j9EB_1TObM");
+    params.put("out_trade_no", "20251029153140");
+    params.put("result_code", "SUCCESS");
+    params.put("return_code", "SUCCESS");
+    params.put("time_end", "20251029153852");
+    params.put("total_fee", "1");
+    params.put("trade_type", "JSAPI");
+    params.put("transaction_id", "4200002882220251029816273963B");
+    // 添加一个未知字段
+    params.put("unknown_field", "unknown_value");
+    
+    // 计算正确的签名 (包含未知字段)
+    String correctSign = createSign(params, WxPayConstants.SignType.MD5, MCH_KEY);
+    params.put("sign", correctSign);
+    
+    // 创建 XML
+    StringBuilder xmlBuilder = new StringBuilder("<xml>");
+    for (Map.Entry<String, String> entry : params.entrySet()) {
+      xmlBuilder.append("<").append(entry.getKey()).append(">")
+        .append(entry.getValue())
+        .append("</").append(entry.getKey()).append(">");
+    }
+    xmlBuilder.append("</xml>");
+    String xml = xmlBuilder.toString();
+    
+    System.out.println("测试 XML (包含未知字段 unknown_field):");
+    System.out.println(xml);
+    System.out.println("正确的签名 (包含未知字段计算): " + correctSign);
+    
+    // 解析 XML
+    WxPayOrderNotifyResult result = WxPayOrderNotifyResult.fromXML(xml);
+    Map<String, String> beanMap = result.toMap();
+    
+    System.out.println("\ntoMap() 结果:");
+    TreeMap<String, String> sortedMap = new TreeMap<>(beanMap);
+    for (Map.Entry<String, String> entry : sortedMap.entrySet()) {
+      System.out.println("  " + entry.getKey() + " = " + entry.getValue());
+    }
+    
+    // 检查 unknown_field 是否存在
+    boolean hasUnknownField = beanMap.containsKey("unknown_field");
+    System.out.println("\ntoMap() 是否包含 unknown_field: " + hasUnknownField);
+    
+    // 验证签名
+    String verifySign = createSign(beanMap, WxPayConstants.SignType.MD5, MCH_KEY);
+    System.out.println("原始签名: " + result.getSign());
+    System.out.println("计算签名: " + verifySign);
+    
+    // 这个测试验证修复后 toMap() 能正确包含所有字段
+    Assert.assertTrue(hasUnknownField, "toMap() 应该包含 unknown_field");
+    Assert.assertEquals(verifySign, result.getSign(), "签名应该匹配");
+  }
+  
+  private static String createSign(Map<String, String> params, String signType, String signKey) {
+    StringBuilder toSign = new StringBuilder();
+    for (String key : new TreeMap<>(params).keySet()) {
+      String value = params.get(key);
+      if (value != null && !value.isEmpty() && !NO_SIGN_PARAMS.contains(key)) {
+        toSign.append(key).append("=").append(value).append("&");
+      }
+    }
+    toSign.append("key=").append(signKey);
+    return DigestUtils.md5Hex(toSign.toString()).toUpperCase();
+  }
+}