When traditional control methods are used in low-speed region of wind power generation power systems, there are several problems including low efficiency of wind energy conversion, poor performance of tracking wind speed, and large fluctuation range of generation torque, etc. Against these problems, an improved control strategy, which combines super twisting algorithm with optimal torque method for maximum power point tracking, is proposed. In order to further improve the control performance, the particle swarm algorithm is used to optimize the controller parameters. Finally, the wind rotor angular velocity, generator output power, generator torque and power coefficient are used as evaluation indexes, and the feasibility and effectiveness of the proposed method are verified on Matlab/Simulink platform. The simulation results show that the proposed control strategy can effectively suppress the chattering of generator torque while improving the capability of capturing the maximum wind energy. This work is supported by National Natural Science Foundation of China (No. 51477109 and No. 61703296).