Abstract: For revealing the mechanism of abnormal gas emission caused by the change of atmospheric pressure, the effect of rapid and continuous reduction of atmospheric pressure on mine ventilation system is studied by means of theory and case analysis. The research shows that the decrease of atmospheric pressure changes the natural ventilating pressure by reducing the air density. As an important component of the mine ventilation power, the sharp decrease of natural ventilating pressure will lead to the reduction of mine air volume and the increase of gas concentration. The period of sharp decrease of atmospheric pressure is the dangerous period of abnormal gas emission. It is an important reason for abnormal gas emission caused by violent fluctuation of atmospheric pressure that the change of natural ventilating pressure occupies a big ratio of the total ventilation resistance. The stability of mine ventilation system can be enhanced by appropriately increasing the total resistance of mine ventilation so as to weaken the influence of natural ventilating pressure change. Atmospheric pressure monitoring, gas extraction, and fine regulation of air volume can control gas emission caused by atmospheric pressure change to a certain extent.