A distributed less-mass energy control strategy based on SOC of lithium ion battery was designed for aerospace emergency power supply system. Lithium battery SOC measurement is the basis of the control strategy, the article puts forward the project solution to the two problems of the calibration of the battery capacity in the SOC measurement process and the determination of the open circuit voltage and the initial SOC curve. The bidirectional Buck-Boost converter is selected as the energy transmission medium. According to the bus demand, constant voltage discharge mode is chosen. Combined with the characteristics of lithium battery pack, constant current and constant voltage charging method is selected. Based on the above basis, simulation and experimental verification is conducted on the design multiple battery groups coordinated charging and discharging energy management strategies. It also provides a new direction for electric vehicle energy management system.