When multiple photovoltaic power sources are connected in parallel in the DC distribution network, photovoltaic with different output have differences in the regulation capacity of unbalanced power of the system. In order to make full use of the power margin of photovoltaic to adjust the DC bus voltage, this paper proposes an adaptive droop control of DC distribution network considering the photovoltaic output power margin. The voltage signals of the input and output terminals of the PV side converter are used to judge the system load change and the output of the photovoltaic power supply. On the basis of traditional droop control, the droop coefficient is modified based on the input voltage deviation of PV side converter to realize the reasonable distribution of the unbalanced power between photovoltaic power sources with different power margin. The output impedance characteristic model of PV side converter is established, and the adaptive droop control proposed in this paper can effectively improve the stability of multi PV parallel connected DC distribution system. Finally, the effectiveness of the proposed control method is verified by MATLAB/simulink platform simulation.