The simulation models of electrical parking brake (EPB) actuator in Simulink software were built, including DC motor model, lead-screw model and inner friction analysis models. The inner friction concluded viscous friction, Coulomb-friction and etc. In order to save cost, a method for controlling EPB system by using on-off controller was proposed. The simulation results and experiment results were compared to verify the feasibility of the proposed simulation model and on-off controller used in EPB system. 