Output power of direct drive permanent magnet synchronous generator (PMSG) system is directly influenced by the rotational speed of generator. In order to improve the output power of small-scale direct drive PMSG, through the analysis of working characteristics of wind turbine and the maximum power tracking principle, this paper points out the shortcomings of classical hill-climbing method and puts forward a new variable step hill-climbing method. Using the relationship between the speed disturbance of time and power change gradient to decide the next step disturbance can improve the system dynamic response, and the direction of disturbance is consistent with the classical hill-climbing method. In the vicinity of the maximum power point, when power fluctuation is less than a certain value, the search will be stopped to realize the quickness and stability of maximum power point tracking. Simulation results verify the feasibility of the method.