Abstract: This paper analyzes the working principle of co-rotating pneumatic air door. Combined with the actual characteristics of pressure balancing ventilation system in Bulianta Coal Mine, the paper summarizes some important points and advantages of the application of co-rotating pneumatic air door in pressure balancing ventilation system, and the air door has been improved and optimized. In the case that all other conditions of the pressure balancing ventilation system remain unchanged, after replacing the traditional balancing electric damper, the pressure difference between the inside and outside of the air door is increased from 400 Pa to 550 Pa. The total air volume of the working face rises from 2 050 m³/min to 2 250 m³/min. The air leakage of the air door was obviously reduced. It is proved that the air door can achieve better results in the pressure balancing ventilation system.