A stand-alone photovoltaic (PV) power system with storage batteries is designed. Power from PV modules is sent to the load on the DC bus through a DC-DC converter, and a bidirectional converter is used for storage batteries. The storage batteries will be charged when the power from PV modules is more than the power that load needs; Storage batteries provide power for load when the power from PV modules is less than the required. Adopt the maximum power point tracking algorithm to ensure PV modules provide the maximum power under certain conditions. In terms of software, this paper describes the control procedure in the whole and gives the algorithm and software design flow chart. The simulation model is built based on MATLAB/Simulink. The simulation and experimental results prove the rationality and feasibility of stand-alone PV power system.