$str = "04aol汉字";
$pattern = "/^(\d{2})([A-Za-z]{3})([".chr(0xa1)."-".chr(0xff)."]+)$/";
if(preg_match($pattern, $str, $tmp))
{
　　var_export($tmp);
}

array (
　　0 => '04aol汉字',
　　1 => '04',
　　2 => 'aol',
　　3 => '汉字',
)