The utility model relates to a mainly relate to a mine ventilation system adjusts automatic pressure relief device that facility was used, especially relate to the air door. When blasting the accident in the pit in the colliery, this air door rupture disk (6) automatic pressure release that breaks that inclines is down with the wind strikeing under the pressure effect, and pressure port (1) can be along bearing (3) upswing to make explosion airflow pass through rapidly, protected the door body, after the explosion finished, pressure port (1) was under the effect of gravity, and swing naturally downwards with fixed magnet (7) closely laminating of the side door body down, has realized that the tunnel after the explosion is sealed to prevent and treat the mobile disorder of air in the pit, the normal operating of underground ventilation system has been protected to the prevention and cure inverted ventilation, has important realistic meaning to safeguarding safety in production in the pit.