diff --git a/VOL.Core/Utilities/JSSaTokenSignHelper.cs b/VOL.Core/Utilities/JSSaTokenSignHelper.cs
new file mode 100644
index 0000000..5a859ec
--- /dev/null
+++ b/VOL.Core/Utilities/JSSaTokenSignHelper.cs
@@ -0,0 +1,124 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace VOL.Core.Utilities
+{
+    public static class SaTokenSignHelper
+    {
+        /// <summary>
+        /// 根据业务参数生成 Java Sa-Token Sign 兼容的 QueryString
+        /// 自动生成 timestamp 和 nonce，如果外部未提供
+        /// </summary>
+        /// <param name="paramMap">业务参数字典（可包含 teacherNo 等）</param>
+        /// <param name="secretKey">应用密钥</param>
+        /// <param name="channel">应用编码，例如 sk-yuedong</param>
+        /// <returns>带 sign 的完整 QueryString</returns>
+        public static string BuildQueryString(Dictionary<string, object> paramMap, string secretKey)
+        {
+            if (paramMap == null)
+                paramMap = new Dictionary<string, object>();
+
+            // 1️⃣ TreeMap 排序（ASCII 升序）
+            var sorted = new SortedDictionary<string, string>(StringComparer.Ordinal);
+            foreach (var kv in paramMap)
+                sorted[kv.Key] = kv.Value.ToString();
+
+            // 2️⃣ 拼接签名字符串 k=v&k=v&...&key=secretKey
+            var sbSign = new StringBuilder();
+            foreach (var kv in sorted)
+                sbSign.Append(kv.Key).Append("=").Append(kv.Value).Append("&");
+            sbSign.Append("key=").Append(secretKey.Trim());
+
+            string sign = Md5(sbSign.ToString());
+
+            // 3️⃣ 拼接 QueryString（保留外部字典原顺序）
+            var sbQuery = new StringBuilder();
+            foreach (var kv in paramMap)
+                sbQuery.Append(Uri.EscapeDataString(kv.Key))
+                       .Append("=")
+                       .Append(Uri.EscapeDataString(kv.Value.ToString()))
+                       .Append("&");
+
+            sbQuery.Append("sign=").Append(sign);
+
+            return sbQuery.ToString();
+        }
+
+
+        /// <summary>
+        /// 构建 POST JSON 上传接口的 QueryString（包含 sign）
+        /// ⚠️ 不与 GET 共用，避免误用
+        /// </summary>
+        public static string BuildPostJsonQueryString(
+            Dictionary<string, object> paramMap,
+            string secretKey,
+            string jsonBody)
+        {
+            if (paramMap == null)
+                throw new ArgumentNullException(nameof(paramMap));
+
+            if (string.IsNullOrWhiteSpace(jsonBody))
+                throw new ArgumentException("POST JSON body 不能为空");
+
+            // 1️⃣ 参与签名的参数（TreeMap + ASCII 排序）
+            var signParams = new SortedDictionary<string, string>(StringComparer.Ordinal);
+
+            foreach (var kv in paramMap)
+                signParams[kv.Key] = kv.Value.ToString();
+
+            // ⭐ POST JSON 特有：整个 body 作为 reqbody
+            signParams["reqbody"] = jsonBody;
+
+            // 2️⃣ 拼接签名字符串
+            // k=v&k=v&...&key=secretKey
+            var sbSign = new StringBuilder();
+            foreach (var kv in signParams)
+                sbSign.Append(kv.Key)
+                      .Append("=")
+                      .Append(kv.Value)
+                      .Append("&");
+
+            sbSign.Append("key=").Append(secretKey.Trim());
+
+            string sign = Md5(sbSign.ToString());
+
+            // 3️⃣ 构建 URL QueryString（⚠️ 不包含 reqbody）
+            var sbQuery = new StringBuilder();
+            foreach (var kv in paramMap)
+                sbQuery.Append(Uri.EscapeDataString(kv.Key))
+                       .Append("=")
+                       .Append(Uri.EscapeDataString(kv.Value.ToString()))
+                       .Append("&");
+
+            sbQuery.Append("sign=").Append(sign);
+
+            return sbQuery.ToString();
+        }
+
+        /// <summary>
+        /// MD5 小写 32 位
+        /// </summary>
+        private static string Md5(string input)
+        {
+            using var md5 = MD5.Create();
+            var bytes = md5.ComputeHash(Encoding.UTF8.GetBytes(input));
+            var sb = new StringBuilder();
+            foreach (var b in bytes)
+                sb.Append(b.ToString("x2"));
+            return sb.ToString();
+        }
+
+        /// <summary>
+        /// 生成随机字符串 nonce，可指定长度
+        /// </summary>
+        public static string RandomString(int length = 20)
+        {
+            const string chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+            var random = new Random();
+            return new string(Enumerable.Repeat(chars, length).Select(s => s[random.Next(s.Length)]).ToArray());
+        }
+    }
+}