The stability of the brake system is a key factor for the vehicle safety.It is important for the air braking system's stability to shorten the time lag between the front brake and the rear brake,the reasonable disposal of the air pipeline and the optimization of the braking system design.A test bench is developed to test the performance of the air braking system,which is mainly made of pressure sensors,signal amplifiers,data acquisition system,computer,pressing air resource and so on.Based on this test bench,the reaction time of the system while braking and abandoning brake can be measured.Using this test bench,the performances of the air braking system of a certain commercial vehicle is detected.Compared with the actual road test,it can save the cost and the time for experiment largely.