The energy storage unit of large capacity energy storage equipment is usually obtained by series-parallel connection of a large number of battery packs. It is difficult to ensure that each battery pack works according to the same charging and discharging curve because of the different parameters of each battery pack. It is very easy to cause overcharging and over discharging of single battery pack and reduce the life and performance of energy storage equipment. Aiming at the above problems, a balancing control strategy of cascaded H-bridge energy storage converter is proposed. Firstly, the working principle and internal energy transfer mode of cascaded H-bridge energy storage converter are explained. Secondly, the working state of each battery pack and the sub-module electricity are calculated by the current charge state and average charge-discharge curve of each battery pack. Capacitance voltage command value is combined with sorting algorithm and nearest level approximation method to realize the sub-module capacitance voltage stability and make N-1 battery pack work according to the average electric curve (N is the number of H-bridge modules). Finally, the feasibility of the control algorithm is verified by MATLAB/Simulation simulation platform.