Because the sliding mode control system based on traditional exponent reaching law has the low complexity, it is widely used in the permanent magnet synchronous motor (PMSM). However, sliding mode control system has obvious chattering when the approaching motion is carried out , thus its accuracy can not cope with the complex situation. In order to restrain chattering and improve the ability of dealing with external disturbance in permanent magnet synchronous motor control system, a novel exponent reaching law is firstly proposed, and a continuous switching function is used to smooth the control signal. In order to further reduce high frequency disturbance caused by signal processing, an integral type sliding mode controller is adopted. Aiming at the estimation accuracy of rotor position, a rotor position observer based on the Luenberger linear observer is designed.. The simulation results show that the integral sliding mode controller based on the novel exponent reaching law and rotor position observer not only