In the present study, we proposed a simulation model of vacuum booster with AMESIM software to predict the output characteristic. And we performed the sensitivity analysis of output characteristic with main design parameters, such as diaphragm diameter. All of these parameters are main design parameters in the procedure of vacuum booster design. The simulation results of this paper offer qualitative information of vacuum booster output. Therefore, the simulation results of this paper will be used effectively for the design procedure of vacuum booster in the industrial field.