Abstract: In order to solve problems of slow tracking speed and poor accuracy of the maximum power point tracking technology such as fixed voltage method, incremental conductance method and so on used in photovoltaic power system at present, a variable step size incremental conductance algorithm was proposed. For controlling grid current and DC bus voltage of photovoltaic power system, a new method was design by use of input output feedback linearization control technology, which allows control of both power factor and DC bus voltage using the same control algorithm. The model of photovoltaic power system was established and simulated based on the variable step size incremental conductance algorithm and input-output feedback linearization control technology in Matlab/Simulink, and the results showed that using the input-output feedback linearization control technology to control inverter makes changes of solar irradiation and temperature do not affect power factor of power grid, and the variable step size incremental conductance improves dynamic and static performances of the photovoltaic power system and reduces the total harmonic distortion of current in the power grid.