In order to solve the imbalance of state of charge(SOC)caused by energy storage units,an improved SOC equalization scheme based on exponential droop control is proposed.The scheme establishes a functional relationship between the amplification factor n in the exponential droop control and the SOC difference between energy storage units, so that it can gradually increase from small to large along with the change of the SOC difference between energy storage units,which improves the equalization speed of SOC,and also solves the problem that the power response speed and the power convergencespeed cannot be considered simultaneously in the equalization process.At the same time,the capacity weighting factor is introduced into the droop coefficient to eliminate the influence of capacity on SOC equilibrium. Finally,the relevant models are built in MATLAB/Simulink and the simulation verifies the correctness and effectiveness of the proposed scheme.