In order to solve the problem of bus voltage fluctuation caused by the mismatch between photovoltaic output power and load consumption power in off-grid photovoltaic DC micro-grid, the hybrid energy storage device combining battery and super capacitor is usually used to compensate the power of the system. Generally, the power distribution of the energy storage device is carried out through droop control. The traditional droop control is difficult to achieve the droop coefficient according to different frequency characteristics, and the distribution characteristics of power fluctuation can also be affected by line impedance and so on. Based on the traditional droop control, this paper proposes a fuzzy-droop control strategy, which optimizes the droop coefficient in real time, suppresses the negative influence caused by the internal factors of the system, and realizes the reasonable distribution of the unbalanced power between the battery and the super capacitor in the DC micro-grid. Matlab/Simulink simulation shows that the proposed fuzzy-droop control strategy can effectively realize the power regulation in DC micro-grid, suppress the fluctuation of bus voltage, and improve the robustness of the system.