For the islanded DC microgrid, it is difficult for the traditional "voltage-power" droop control to make the distributed generation to supply the load power accurately according to the droop coefficient. This is because of the unmatched line impedances and local loads. An island DC microgrid power allocation control strategy is proposed by using adaptive high-pass filtering droop control. By introducing the sample-and-holder, the droop coefficient is modified when the actual output power of DG deviates from the expected output power. At the same time, the high-pass filter control guarantees good bus voltage quality. Finally, based on the platform of RTDS, an experimental scheme under different working conditions is designed and the results verify the effectiveness of the proposed control strategy. This work is supported by National Natural Science Foundation of China (No. 61873159), Shanghai Committee of Science and Technology Projects (No. 18020500700), Shanghai Green Energy Grid Engineering Technology Research Center Projects (No. 13DZ2251900), “Electrical Engineering” Shanghai Class II Plateau Discipline, and Shanghai key Laboratory of Power Station Automation Technology.