Abstract: In view of problems of big stable state error, large chattering and poor tracking speed existed in conventional equivalent sliding mode controller in vector control system of asynchronous motor, an improved equivalent sliding mode controller was designed. The controller uses improved switching control function to improve dynamic control performance of the motor. The simulation results show that the improved controller can effectively reduce buffeting, improve dynamic response speed and enhance the robustness of the system compared with the conventional PI controller and conventional equivalent sliding mode controller.