To meet the need of grid development in new generation, an aggregation theory integrating with Ecology, Behavioral Science, Organization Theory as well as big data analysis method is proposed. The aggregation theory describes the power system operation features, evolution law, and dispatch model from the new perspective of Ecology, which can guide the design of the behavior norm, operation mode, and dispatch scheme of power grid operation. It makes full use of massive data and adopts orgnization group operation mode which is more universal and more flexible, conforms to the development tendency characterized as power grid mass data sources, and being distributed, diversified, and intelligent, and guarantees and speeds up the evolution process and modern power grid, which is practical, prospective, and instructive.