Aiming at the problem of state-of-charge (SoC) imbalance among energy storage units in DC microgrids caused by line impedance mismatch, which can lead to overcharging or over-discharging of individual units, an adaptive droop control strategy based on successive compensation of line impedance is proposed. First, in the line impedance compensation control, the process is divided into three stages. In the first stage, the droop coefficient is updated by integrating the output current. In the second stage, the output current at the intermediate integration moment is used as the reference current to restore the bus voltage. In the third stage, the current sharing error is estimated to update the iterative signal. In addition, a switching signal is introduced to control the transitions between stages, and a consistency algorithm is used to calculate the iterative signal for updating the switching signal. Next, in the SoC balancing control, the compensated line impedance and a monotonic function associated with the SoC information are incorporated into the adaptive droop control to achieve SoC balancing and current sharing among the energy storage unit. Finally, an experimental prototype with multiple energy storage units is built to verify the feasibility and effectiveness of the proposed strategy.