A control strategy of voltage balancer which is suitable for DC microgrid load unbalance is proposed to provide a stable and reliable DC power for DC microgrid system clients. According to voltage balancer main circuit topology, the small signal model of voltage balancer was established through state space averaging method. PWM control technology and PI sectors were introduced on the basis of the analysis of the circuit model to achieve the output voltage balance control and ensure the stability of the output of the balancer. It also suppresses the influence of load disturbance on the DC output voltage. A prototype with capacity size of 15 kW was built in MARTALB simulation software and the case of load variations on voltage balancer was simulated to verify the proposed method. Simulation results show the correctness of the theory and validity of proposed control strategy.