The mismatch of converter output line impedance reduces the power distribution accuracy of distributed energy storage units in an islanded DC microgrid and affects the balance of the state of charge, while the traditional droop control causes the drop of DC bus voltage. To address this problem, the proposed strategy firstly defines the SOC equalization factor and analyzes the effect of each factor change on it; secondly, the power distribution factor is combined with the converter output voltage as the information exchange factor, and the correction term of the sag control reference voltage is obtained through the integrator. At the system’s steady state, the proposed strategy achieves SOC equalization of each DESU, output power distribution according to capacity, and the average bus voltage is stabilized at a given value; finally, the simulation results based on the model verify the effectiveness of the proposed strategy.