Abstract: Aiming at the problems of uneven power distribution and bus voltage drop caused by the change of cable impedance and working condition in the droop control of direct current(DC) microgrid, a combined control strategy based on improved sparrow search algorithm to set droop coefficient and hierarchical droop control is proposed. Firstly, the improved algorithm combines the dynamic discoverer with the adaptive helix factor to improve the optimization accuracy and convergence speed of the original algorithm. In the process of setting the droop coefficient, the droop coefficient and voltage compensation intercept are taken as the search dimension, the DC bus voltage and the output voltage and current of each micro source are sampled, and the deviation from the target value is calculated respectively. The sum of the deviation is taken as the objective function, and the optimal droop parameter is obtained through iterative updating. Then, the output voltage and current of DC microgrid are detected in real time to diagnose the change of DC microgrid working condition, and the optimal droop parameters are adjusted for hierarchical control. Finally, through simulation analysis, it is verified that this proposed method can achieve good control effect under the conditions of micro source fault disconnection, bus load switching and local load switching.