Vacuum booster assembly with master cylinder is an important safety part for M1 category vehicles hydraulic braking system,but the relevant national standards has not been formed.According to automotive industry standards,input-output characteristics of the vacuum booster and brake master cylinder operating characteristics were analyzed,then bench test was made.In accordance with industry technical specifications,operating characteristics of the vacuum booster assembly with master cylinder were studied,and the results were analyzed.Experimental study on the characteristics of the assembly provides a reference for the development of the vacuum booster assembly with master cylinder testing and evaluation.