There are obvious advantages in collaborative work for the system based on the multi-agent technology. According to a concrete microgrid in this paper, multi-agent control system is designed based on the microgrid control goals. The structure of multi-agent microgrid control system and the specific functions of each agent are proposed, expounding the microgrid coordinated control strategies at the grid-connected and islanded state respectively. The model of microgrid based on the multi-agent is established in the MATLAB/SIMULINK. The simulation model has simulated the microgrid's characteristics of running operation performance both under the grid-connected and islanded situation. Simulation results show that multi-agent microgrid control system can fully satisfy the requirement of power balance control and inhibit frequency fluctuation under the two situation.