Abstract: In view of the problem of transient blowing-out in switchover process of ventilators of traditional ventilation system of coal mine, the paper proposed an optimization scheme of ventilation system of coal mine of switchover of ventilations without blowing-out. The scheme adds a louvered flat-type air door at each top of the two wind roadways based on traditional ventilation system of coal mine to keep constant of underground air flow in switchover process of ventilators. The actual application validated feasibility and practicality of the scheme.