With large-scale coal and gas outburst as the object, this paper established mathematical model of mine gas migration during gas outburst based on the analysis of source ventilation network. And then, a real mine accidents was taken as examples to simulate the process of airflow disorder and the change trace of the fan operation point. Under the direct action of the swarming force of gas “outburst source”, the airflow moves mainly along the major airway, even can reversed into the main intake working or the auxiliary shaft. After the outburst, because of the gas residual in the airways of the ventilation system, the natural gas air pressure could maintain reverse current for a period of time probably. Under the action of the main fan, the mine ventilation would recover gradually, but the gas natural air pressure could also bring local airflow reverse. The reversed airflow can make the range of gas flow keep expanding and the states of the airflow changing and complicated, which could increase the probability of gas explosion greatly.