diff --git a/qiniu/rs.php b/qiniu/rs.php
index 1166b5d8..d2a94125 100644
--- a/qiniu/rs.php
+++ b/qiniu/rs.php
@@ -32,7 +32,7 @@ public function MakeRequest($baseUrl, $mac) // => $privateUrl
 
 function Qiniu_RS_MakeBaseUrl($domain, $key) // => $baseUrl
 {
-	$keyEsc = rawurlencode($key);
+	$keyEsc = str_replace("%2F", "/", rawurlencode($key));
 	return "http://$domain/$keyEsc";
 }
 
diff --git a/tests/RsTest.php b/tests/RsTest.php
index 2368198c..b02375a2 100644
--- a/tests/RsTest.php
+++ b/tests/RsTest.php
@@ -88,5 +88,11 @@ public function testBatchDeleteMoveCopy()
 
 		Qiniu_RS_BatchDelete($this->client, array($e2, $e3, $e4));
 	}
+
+	public function testUrlEncode() {
+		$url = Qiniu_RS_MakeBaseUrl("www.qiniu.com", "a/b/c d");
+		var_dump($url);
+		$this->assertEquals($url, "http://www.qiniu.com/a/b/c%20d");
+	}
 }