diff --git a/wecom/callback-inbound.js b/wecom/callback-inbound.js
index a241670..c08824c 100644
--- a/wecom/callback-inbound.js
+++ b/wecom/callback-inbound.js
@@ -168,7 +168,8 @@ export function parseCallbackMessageXml(xml) {
 // ---------------------------------------------------------------------------
 
 async function loadLocalReplyMedia(mediaUrl, config, agentId, runtime) {
-  const normalized = String(mediaUrl ?? "").trim();
+  const normalized = !String(mediaUrl ?? "").trim().startsWith("\\") ? String(mediaUrl ?? "").trim() :
+                      String(mediaUrl ?? "").trim().replace("\\", "/");
   if (!normalized.startsWith("/") && !normalized.startsWith("sandbox:")) {
     throw new Error(`Unsupported callback reply media URL scheme: ${mediaUrl}`);
   }