The parameters of the controller are optimized by genetic algorithm, in order to improve the control method of active power filter in defects at the high frequency chattering of the sliding mode and the controller performance. The principle of three-phase three wire active power filter is introduced and the design of the optimization of controller parameters of genetic algorithm is analyzed in detail. The exact values of the parameters of the controller are achieved. According to the error of the compensation current and instruction current, sliding mode variable structure controller is obtained. Though the simulation of experiment of the traditional PI control method and the optimized sliding mode control, the results demonstrate that the proposed method can obtain quick response, simple algorithm and better jitter suppression and robustness.