Abstract: In view of the engineering application of MMC-BESS technology, this paper provides theoretical basis and practical steps and methods for SOC balance control parameter design from four dimensions of modulation, efficiency, submodule capacitor voltage balancing, and device selection. To improve the speed of SOC balance control, the SOC balance control method of setting different control parameters in sections between submodules in the bridge arm is proposed. Based on the proposed demonstration project, the control parameters are designed. In addition, the rationality of control parameter design and the effectiveness of segmented control parameters to accelerate SOC balance control are verified by simulation.