function read_utf8($utf8_text){
     return htmlspecialchars(iconv("UTF-8","gb2312",$utf8_text));
}
function unescape($str){
     $ret = '';
     $len = strlen($str);

     for ($i=0;$i<$len;$i++){
         if ($str[$i] == '%' && $str[$i+1] == 'u'){
             $val = hexdec(substr($str, $i+2, 4));

             if ($val < 0x7f) $ret .= chr($val);
             else if($val < 0x800) $ret .= chr(0xc0|($val>>6)).chr(0x80|($val&0x3f));
             else $ret .= chr(0xe0|($val>>12)).chr(0x80|(($val>>6)&0x3f)).chr(0x80|($val&0x3f));

             $i += 5;
         }else if ($str[$i] == '%'){
             $ret .= urldecode(substr($str, $i, 3));
             $i += 2;
         }else $ret .= $str[$i];
     }
     return read_utf8($ret);
}
echo unescape('%u6211%u4EEC%u90FD%u53BB%u6B7B');

这个可以在gb2312页面中使用。如果是其他编码的页面请修改第二行的gb2312。

function read_utf8($utf8_text){
      return htmlspecialchars(iconv("UTF-8","gb2312",$utf8_text));
}
忘了把htmlspecialchars去掉了……