In order to maximize the use of solar energy, to avoid the external environment or the load power oscillation, steady-state accuracy problem of low mutation when the traditional algorithm in maximum power point tracking process, this paper proposes a variable step hill-climbing algorithm PWM of photovoltaic power generation system. The method is to determine the disturbance direction and step size in single iteration to track the maximum power point. The output characteristics of variable step hill-climbing algorithm MPPT in the steady state and dynamic under the two conditions of the system is validated through two aspects of simulation and experiment, and the performance of the fixed step climbing method compared to the MPPT system for a comprehensive assessment. The results showed that the effectiveness of the variable step hill-climbing algorithm, this method can quickly and accurately search the maximum power point of PV array, reduce the response time, recovery time and power oscillation, improves the energy conversion efficiency of photovoltaic power generation system.