Aiming at the motor drive control system of electric vehicle for using permanent magnet synchronous motor with vector control, in order to improve its capability of resisting load disturbance, and when the electric vehicle was running at low speed, it could output large torque. A sliding mode speed controller was designed to improve the exponential reaching law of sliding mode variable structure control. In order to reduce chattering of the sliding mode variable structure control, the saturation function was introduced instead of the sign function. At the same time, considering the hysteresis in sliding mode speed controller, the saturation function and the integral signal are multiplied, so that the response speed could be improved and the disturbance rejection capability could be enhanced. Simulation results showed that when the load was changed, the sliding mode speed controller had strong stability, which could made the electric vehicle output large torque at low speed.