In order to utilize solar energy effectively, it is necessary to study on Maximum Power Point Tracking (MPPT) in photovoltaic power generation system. In this paper, single stage photovoltaic power generation system is studied and the mathematical model of photovoltaic array is established under any arbitrary environment. Due to the nonlinear output characteristic of photovoltaic array, fuzzy control is introduced to realize MPPT. It is presented perturb and observe (P&O) of duty cycle for fuzzy control in MPPT control strategy .The simulation is carried out based on the proposed algorithm. Compared with the conventional duty cycle of P&O method, it can track the maximum power point quickly and accurately.