$s = "*id=3,express_no=25,ename=quanri,*id=4,express_no=17,ename=kuaidi,";

$t = array();
foreach(explode('*', $s) as $v) {
  if(empty($v)) continue;
  parse_str(str_replace(',', '&', $v), $t);
  $r[] = $t;
}
print_r($r);