Abstract When the grid connected photovoltaic power is scarce, the energy storage device can play an important role in power supplement to stabilize the grid. A bi-directional three-level Buck / Boost converter topology has been studied, and its working principle has been introduced in detail in this Paper. Based on the working characteristics of energy storage battery, combined with the battery “Three-stage” charging method, the voltage and current closed-loop control strategy of three-level DC/DC converter has been studied. It can work in constant power charging and discharging as well as constant current charging and discharging. The simulation platform of 50KW energy storage power device has been set up, which can freely switch from charging state to discharging state. The results show that the research on bidirectional three-level DC / DC converter is feasible and effective.