diff --git a/server/app/common.php b/server/app/common.php
index deb4deb0832c031e79452bb6df6f648fdabcfc35..3449a34d2e168d6b930d4fa8f7dd95d0f2b2a8bd 100644
--- a/server/app/common.php
+++ b/server/app/common.php
@@ -195,7 +195,8 @@ function download_file($url, $saveDir, $fileName)
 function clear_file_domain($content)
 {
     $fileUrl = FileService::getFileUrl();
-    return str_replace($fileUrl, '/', $content);
+    $pattern = '/<img[^>]*\bsrc=["\']'.preg_quote($fileUrl, '/').'([^"\']+)["\']/i';
+    return preg_replace($pattern, '<img src="$1"', $content);
 }