For photovoltaic power generation system of solar energy maximum power point tracking (MPPT) algorithm, is proposed based on interpolation calculation method and variable step length hysteresis comparison method combined with improved algorithm. The algorithm effectively overcomes the misjudgment and shock phenomenon existing in the traditional MPPT algorithm, and improve the accuracy of the algorithm and the tracking speed, under the Matlab/Simulink MPPT control algorithm of modeling and simulation, the simulation results show that the proposed algorithm can effectively improve the system dynamic response speed and steady-state accuracy.