Abstract: In order to improve the economy and stability of wind-solar-storage DC microgrids,this paper studies the optimal configuration of system capacity. Firstly,based on the proposed wind-solar-storage-grid operation scheduling strategy,the capacity optimal allocation model of wind-solar-storage DC microgrid is established with the annual average comprehensive cost and power deviation rate as the objective functions,considering the safe and stable operation of the system as the constraint conditions. Then,aiming at the problem that the sparrow search algorithm is easy to fall into the local optimum and insufficient convergence accuracy when solving the optimal configuration model with non-zero solution,an improved sparrow search algorithm integrating Tent chaos,spiral search,Levy flight strategy and mutation disturbance is proposed. Furthermore,the improved sparrow search algorithm is compared with normal sparrow search algorithm,particle swarm optimization algorithm and whale optimization algorithm using four standard test functions. Finally,an example analysis is carried out with the Qianjiang big data center as the application object,and the feasibility and effectiveness of the model and algorithm are verified.