In order to maximize the power of photovoltaic generation system, it is necessary to track the maximum power point (MPP). A new control algorithm of photovoltaic (PV) was proprosed, which applied constant voltage tracking method (CVT) to adjust the working point around the MPP and ensure fast tracking when external conditions or loads changed suddenly. The algorithm used the optimal gradient method (OG) to make optimization of the steady-state characteristic and could effectively reduce the output power of photovoltaic array oscillation around maximum power point tracking (MPPT). The experiment and simulation results show that the proposed algorithm could track the MPP rapidly and accurately. And also could improve the energy conversion efficiency of PV generation system by reducing the output power oscillation around MPP.