With the rapid development of photovoltaic industry, photovoltaic power generation has become a new force of renewable energy. However, the influence of power photovoltaic system subjects to different weather conditions and has the characteristics of uncertainty and periodicity. For accurate prediction of photovoltaic power to ensure the stability of power system, this paper uses GA-BP algorithm for prediction and analysis of power generation of photovoltaic system. Results show that the model and method presented in this paper can predict the power output of photovoltaic system and are of more accuracy and certain practical value.