Aiming at the inherent disadvantages of traditional cascade speed regulation system such as serious harmonic pollution and low power factor, a voltage cascade speed regulation system based on PWM inverter was designed.The mathematical model of PWM inverter in dq coordinates was derived in detail. In order to eliminate the coupling and nonlinear, the exact linearization decoupling additional variable structure control strategy was adopted, and the construction of control law was deduced. And the speed current double closed loop PI control was used by the IGBT chopper circuit to get the control chart of the system. Finally the effectiveness of control strategy was simulated by MATLAB. The results proved that the control strategy not only could achieve smooth and stepless speed regulation, but also could achieve the purpose of improving power factor, eliminating harmonic and saving energy.