In term of operating characteristics of the wind turbine based on electromagnetic coupler, torque backstepping slide-model variable structure control and speed backstepping control were respectively applied in maximum power tracking area and constant speed area. A simulation model of a wind turbine based on an electromagnetic coupler in maximum power point tracking was built. The proposed control method had a simple structure and avoids measuring real-time wind speed. The simulation results , which were accomplished in step wind and random wind condition, indicate that this power tracking control scheme had good dynamic and static performance and better robust performance. Compared with torque backstepping and classical OTC, the proposed method could quickly and accurately track the variation of wind and effectively accomplish the goal of maximum power tracking.