Abstract: To solve the problem of the output power of maximum power point tracking system by perturbation and observation（P＆O） method small oscillating around the maximum power point,a fuzzy controller with particle swarm optimization（PSO） algorithm was applied to maximum power point tracking（MPPT） of photovoltaic generation system.The PSO algorithm was applied to optimize the membership function of fuzzy controller and to accomplish real-time adjustment and tracking of step size in order to ensure that the system has a faster dynamic response speed and higher steady-state accuracy in case the light intensity or temperature varies.In this research,simulations and experiments were performed with the perturbation and observation method,the fuzzy control method and the fuzzy controller with PSO algorithm on the same condition,and the result demonstrates the effectiveness and robustness of the proposed method.