With the deepening of the interactive studies on the source network and load of the power grid, the adjustable resources of the power grid are increasing. The interconnected power grid system forms by the interconnection and mutual supply of each power grid in a certain region. It has become the object of attention of scholars at home and abroad. Firstly, the energy optimization management method of the interconnected power grid is proposed by using the hierarchical interconnection structure in this paper. Secondly, taking transferable load as the representative of demand side management, an energy optimization management method of interconnected power network is proposed for the joint dispatching of interconnected power network and distribution network based on source network and load interaction. Finally, numerical examples show that the proposed algorithm outperforms existing algorithms in source grid and load interaction.