DC microgrid is receiving growing attention due to its high efficiency and controllability. With the penetration of renewable energy sources (RES) continuously increasing among modern power systems, DC microgrid has to face the issues of large disturbance in generation/loads owing to the randomness of both RES and power consumption. This paper presents a cooperative control method for islanded DC microgrid combing the advantages of both decentralized control and centralized control. In this cooperative control, the primary control is applied in distributed generators (DGs) to maintain the local voltage autonomously with the proposed droop method; in the secondary control, centralized microgrid center controller (MGCC) regulates the energy storage system (ESS) to participate in power regulation, only when primary control cannot maintain the voltage within a settled range. The effectiveness of the cooperative control method is verified by MATLAB/Simulink simulations.