In this paper, an optimal dispatching method with multi-microgrid for flexible medium voltage DC distribution center is proposed. The control architecture of the medium voltage DC distribution center system is introduced firstly. The local autonomy and collaborative optimization of the system can be achieved by the concentrated controllers. The distribution network, medium voltage DC distribution center and microgrids are modeled separately. For different centralized controllers, different dispatching methods are introduced. A combination of daily dispatching and rolling optimization is adopted by the microgrid concentrated controllers with the goal of minimizing the operating cost of the microgrid. A real-time dispatching method is adopted by the MMC concentrated controller with the goal of minimizing weighted sum of the active loss of the distribution network and the load balancing rate of the line. Finally, the feasibility of the dispatching method is verified by an example. This work is supported by Key Project of China Southern Power Grid (No. GZKJQQ00000417).