Based on analysis of the mathematical model of the brushless DC motor (BLDCM), a method for modeling and simulation of BLDCM speed control system is developed in this paper. The simulation model of BLDCM could be established by combination of the functional blocks and S-functions in MATLAB/SIMULINK. In the double loop of control system, a PID controller was adopted in the speed loop and a current controller was completed in the current loop on the principle of hysteresis current track PWM inverter. The modeling method has merits in rapidity, practicality and has guiding significance to designing actual brushless DC motor control system.