With a high proportion of wind, photovoltaic and other new energy units rapidly connected to the power grid, the provincial flexibility resources have been insufficient to support the balance of “Ensuring Supply” and “Promoting Consumption”. In order to solve the problems of inter-provincial power interconnection and new energy consumption, a two-layer optimization model of inter-provincial power interconnection considering uncertainty weather is constructed from the perspective of the regional center. The modes of inter-provincial exchange power adjustment, intra-provincial unit combination adjustment and inter-provincial unit combination adjustment are established sequentially, and the efficiency of unit combination calculation is improved by the Lagrangian decomposition algorithm. Finally, simulation and experimental verification are carried out based on the regional power grid example. The results show that the proposed model can realize inter-provincial power mutual aid and new energy consumption, and the optimization time is greatly reduced to meet the actual operational needs of the grid.