function replace_unicode_escape_sequence($match) {
  return mb_convert_encoding(pack('H*', $match[1]), 'UTF-8', 'UCS-2BE');
}
$name = '\u65b0\u6d6a\u5fae\u535a';
$str = preg_replace_callback('/\\\\u([0-9a-f]{4})/i', 'replace_unicode_escape_sequence', $name);
echo $str; //输出： 新浪微博 

//咱将上述方案A给封装起来~~~(方案A稳定版+升级+推荐)
class Helper_Tool
{
  static function unicodeDecode($data)
  {  
    function replace_unicode_escape_sequence($match) {
      return mb_convert_encoding(pack('H*', $match[1]), 'UTF-8', 'UCS-2BE');
    }  
 
    $rs = preg_replace_callback('/\\\\u([0-9a-f]{4})/i', 'replace_unicode_escape_sequence', $data);
 
    return $rs;
  }  
}
//调用
$name = '\u65b0\u6d6a\u5fae\u535a';
$data = Helper_Tool::unicodeDecode($name); //输出新浪微博

<"str":"'.$name.'"}';
  $arr = json_decode($json,true);
  if(empty($arr)) return ''; 
  return $arr['str'];
}
$name = '\u65b0\u6d6a\u5fae\u535a';
echo unicodeDecode($name); //输出： 新浪微博