Coordinated optimization and control is an effective way to ensure highly reliable operation of the multi-microgrid system. A scheduling model of a multi-microgrid system based on bi-layer optimization with consideration of Point of Common Coupling (PCC) power control and bilateral bidding is proposed. The upper layer aims at minimizing the PCC power and its fluctuation. The lower is to reduce total cost of the multi-microgrid system. In order to coordinate fair dealing and power allocation between the microgrids, a bilateral bidding strategy is adopted. The simulation results demonstrate that the optimization model can reduce the amount and the fluctuation of the PCC power, and the designed bilateral bidding strategy enables reduction of the overall cost of the multi-microgrid system. This work is supported by National Natural Science Foundation of China (No. 51607105).