<form enctype="multipart/form-data" action="uploadgo.php" method="post"> 
      <input type="hidden" name="max_file_size" value="1000000">文件上传<br />
      <input name="user_file[]" type="file">
      <div id="new_up_down"></div><br />
      <input type="button" name="add_file" value="新增上传" onclick="go_up()"/>
      <input type="submit" value="上传文件"> 
    </form>