diff --git a/rest/client.go b/rest/client.go
index 5a4835b..0d45b71 100644
--- a/rest/client.go
+++ b/rest/client.go
@@ -185,8 +185,6 @@ func (c *Client) chain() http.RoundTripper {
 
 // mergeURL return the merged url with common header and params
 func (c *Client) mergeURL(u *url.URL) (*url.URL, error) {
-	query := make(url.Values)
-
 	if c.baseURL != nil {
 		if u.Host != "" || u.Scheme != "" {
 			return nil, fmt.Errorf("baseURL and request url host/schema can not be set at the same time")
@@ -195,13 +193,21 @@ func (c *Client) mergeURL(u *url.URL) (*url.URL, error) {
 		u.Scheme = c.baseURL.Scheme
 		u.Host = c.baseURL.Host
 		u.Path = path.Join(c.baseURL.Path, u.Path)
-		maps.Copy(query, c.baseURL.Query())
 	}
 
-	// change the url query
-	maps.Copy(query, c.commonQueryParams)
-	maps.Copy(query, u.Query())
-	u.RawQuery = query.Encode()
+	// 收集 baseURL 和 commonQueryParams 中的额外查询参数，
+	// 仅当存在额外参数时才合并并重编码，保留原始 RawQuery 中的特殊字符不被误编码
+	extra := make(url.Values)
+	if c.baseURL != nil {
+		maps.Copy(extra, c.baseURL.Query())
+	}
+	maps.Copy(extra, c.commonQueryParams)
+
+	if len(extra) > 0 {
+		query := u.Query()
+		maps.Copy(query, extra)
+		u.RawQuery = query.Encode()
+	}
 
 	return u, nil
 }
@@ -383,11 +389,13 @@ func (r *Request[T]) getURL(u string) (string, error) {
 		return "", err
 	}
 
-	// change the url query
-	query := newURL.Query()
-	maps.Copy(query, r.queryParams)
-
-	newURL.RawQuery = query.Encode()
+	// 仅当有额外查询参数时才重编码，避免 url.Values.Encode() 将原始 RawQuery 中
+	// 合法的特殊字符（如 CDN 签名令牌里的 '='）误编码为 %3D 导致服务端拒绝请求
+	if len(r.queryParams) > 0 {
+		query := newURL.Query()
+		maps.Copy(query, r.queryParams)
+		newURL.RawQuery = query.Encode()
+	}
 
 	return newURL.String(), nil
 }