Abstract: In order to achieve efficiency,security and sustainability of energy utilization,mainly energy sharing over a wide area and connection of large-scale distributed generator（DG）have to be solved in future distribution network（DN）.Thus an optimization model of energy lines planning is built on the principles of optimal energy distribution and investment economy first.And a methodology of establishing the double-layer structure of energy lines is also proposed.Then based on a twodimensional multi-resolution model of DN with the interconnection of DG,an analysis and calculating method of the maximum allowable capacity of DG considering voltage limits,grid losses and thermal constraints is presented.Finally,simulations are performed on a typical system,and the actual capacity of DG integration for DN with the double-layer structure of energy lines is analyzed as well.It is shown that,compared with traditional network structure,energy resources can not only be locally balanced,but also optimally dispatched and shared over a wide area by the double-layer structure of energy lines.Therefore,the maximum allowable capacity of DG can be increased further.