It is designed to prevent indirect illegal immigration of passengers of different destinations by means of boarding pass exchange or boarding at the wrong boarding gates at airports. By linkage between the Meisha system and the boarding system, it realizes identification checks for the passengers at boarding gates with help of boarding pass scanning equipment, the face image collection and comparison technology and the single gap technology. If the identification document information, flight information or face image comparison data of a passenger do not match in the check, it will sound an alarm.