diff --git a/packages/trpc/src/services/mount.service.ts b/packages/trpc/src/services/mount.service.ts
index b3ac9d3..85b9fef 100644
--- a/packages/trpc/src/services/mount.service.ts
+++ b/packages/trpc/src/services/mount.service.ts
@@ -152,10 +152,21 @@ export const mountService = {
                 username: input.username,
                 password: input.password,
             });
-            await listDirectory(client, input.rootPath || "/");
+            // 1) 先探 WebDAV 根：区分「认证/不是 WebDAV」与「根路径写错」
+            try {
+                await listDirectory(client, "/");
+            } catch (e) {
+                const msg = describeWebdavError(e);
+                if (msg.includes("认证失败") || msg.includes("不是 WebDAV") || msg.includes("连接")) {
+                    return { ok: false, message: `${msg}（探测 WebDAV 根路径 / 时失败）` };
+                }
+                // 根 400 等：仍继续试 rootPath，部分服务根不可列
+            }
+            const root = normalizeWebdavPath(input.rootPath || "/");
+            await listDirectory(client, root);
             return { ok: true, message: "连接成功" };
         } catch (e) {
-            return { ok: false, message: describeWebdavError(e) };
+            return { ok: false, message: describeWebdavError(e, input.rootPath || "/") };
         }
     },
 
@@ -165,7 +176,7 @@ export const mountService = {
     ): Promise<{ entries: DirEntry[]; path: string }> {
         const mount = await mountDao.getByIdForUser(input.mountId, userId);
         if (!mount) throw new TRPCError({ code: "NOT_FOUND", message: "挂载不存在" });
-        const abs = joinWebdavPath(mount.rootPath, input.path);
+        const abs = normalizeWebdavPath(joinWebdavPath(mount.rootPath, input.path));
         try {
             const entries = await withClient(mount, (c) => listDirectory(c, abs));
             entries.sort((a, b) => {
@@ -183,16 +194,17 @@ export const mountService = {
 };
 
 /** 把 webdav/网络底层错误归一化成用户可读的失败原因 */
-function describeWebdavError(e: unknown): string {
+function describeWebdavError(e: unknown, path?: string): string {
     const raw = e instanceof Error ? e.message : String(e);
     const s = raw.toLowerCase();
+    const pathHint = path ? `（路径 ${path}）` : "";
     if (
         s.includes("401") ||
         s.includes("403") ||
         s.includes("unauthorized") ||
         s.includes("forbidden")
     )
-        return "认证失败，请检查用户名和密码";
+        return `认证失败，请检查用户名和密码${pathHint}`;
     if (s.includes("enotfound") || s.includes("eai_again") || s.includes("getaddrinfo"))
         return "无法解析服务器地址";
     if (s.includes("econnrefused")) return "连接被拒绝，请检查地址和端口";
@@ -200,8 +212,18 @@ function describeWebdavError(e: unknown): string {
         return "连接超时";
     if (s.includes("certificate") || s.includes("ssl") || s.includes("tls"))
         return "HTTPS 证书错误";
+    if (s.includes("400") || s.includes("bad request"))
+        return `HTTP 400：服务器拒绝该请求${pathHint}。请确认 WebDAV 地址含正确前缀（如 http://主机:端口/dav），根路径为共享目录且 URL 可用`;
     if (s.includes("404") || s.includes("405") || s.includes("not found"))
-        return "地址不可用（可能不是 WebDAV 服务）";
+        return `地址或路径不存在${pathHint}（可能不是 WebDAV 服务，或根路径不正确）`;
     const short = raw.length > 120 ? `${raw.slice(0, 120)}…` : raw;
     return `连接失败：${short}`;
 }
+
+/** WebDAV 路径：补前导 /、去重斜杠、段级百分号编码（中文/空格） */
+function normalizeWebdavPath(input: string): string {
+    const trimmed = input.trim() || "/";
+    const parts = trimmed.split("/").filter(Boolean);
+    const encoded = parts.map((seg) => encodeURIComponent(decodeURIComponent(seg)));
+    return `/${encoded.join("/")}`;
+}