The invention relates to an optimization method in the field of power system automation, in particular to a layered optimization method of a regional distribution network comprising a micro-grid. The method includes the following steps: (1) building a micro-grid and distribution network combined dispatching model; (2) building an efficiency-maximizing secondary dispatching model of the micro-grid; (3) optimizing the two dispatching models. According to the method, the micro-grid is taken as a controllable unit capable of dispatching independently; through coordinated dispatching of a controllable distributed power supply on the distribution network side, the micro-grid and the distribution network and bi-layer dispatching control of economic dispatch of distributed energy resources inside the micro-grid, the distributed energy resources are used in a maximized manner internally, the regional distribution network power supply and loads are dispatched optimally externally, and acceptance capability of the distraction network to the distributed power supply can be effectively improved.