diff --git a/README.md b/README.md
index f25ab0f..6742f72 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,13 @@
 # php FFI Extend
 Call PHP C API
 
-__Note: On windows, can be define constant `PHP_DLL_FILE_PATH` for specify `php7.dll` or `php7ts.dll` path__
+php DLL(php7.dll,php7ts) find:
+  * like unix os, Usually does not require additional loading
+  * windows,  
+    * first, load user constant `PHP_DLL_FILE_PATH`
+    * second, load directory of predefined constant `PHP_BINARY`
+    * third, load php parent directory of ext directory
+__Note:  constant `PHP_DLL_FILE_PATH` work for like unix OS
 # Reference
 
 ### class `Toknot\FFIExtend` of methods
diff --git a/src/FFIExtend.php b/src/FFIExtend.php
index 7f87f55..f28809e 100644
--- a/src/FFIExtend.php
+++ b/src/FFIExtend.php
@@ -136,7 +136,11 @@ private function initPhpApi()
             self::$ffi = FFI::cdef($code, $phpDll);
         } else {
             $code = str_replace('ZEND_FASTCALL', '__attribute__((fastcall))', $code);
-            self::$ffi = FFI::cdef($code);
+            if(defined('PHP_DLL_FILE_PATH')) {
+                self::$ffi = FFI::cdef($code, PHP_DLL_FILE_PATH);
+            } else {
+                self::$ffi = FFI::cdef($code);
+            }
         }
 
         $this->setZendffi();