For a distributed energy storage island DC microgrid system, an adaptive sag control strategy is proposed to solve the problems whereby traditional sag control strategy cannot achieve the balance of charge state, the power distribution is not accurate and the bus voltage drops. First, by combining the hyperbolic tangent function with the charged state, the range of sag coefficient is limited and adjusted quickly through the characteristics of the hyperbolic tangent function. Then, by adjusting the compensation amount, the voltage corresponding to the sag coefficient is equal, and the compensation strategy of power distribution is designed. Finally, the cable impedance is calculated and a secondary bus voltage compensation strategy is designed. Simulink simulation results show that the proposed control strategy can achieve the balance of the charged state and the precise distribution of power, and the bus voltage can be maintained at the rated value accurately.