In order to better adapt to coal and rock characteristics change, exert the ability of shearer cutting motor effectively and solve the problem of power fluctuation in the shearer cutting motor runtime, a constant power control system of shearer cutting motor based on expert system(ES)is established with the theory and method of expert system. In the system, the haulage speed is adjusted in real-time, to make the cutting motor of shearer run in constant power. The model of control system is constructed by the SIMULINK of MATLAB. The simulation results show that haulage speed can be anticipated in the system, adjustment time is decreased by 0.62s and the power of cutting motor overshoot is decreased by 3.8% than conventional system. The system has sensitive response, small fluctuations and Steady working.