There is currently insufficient consideration of the coordination of the power transmission and distribution network. In considering the optimization of load distribution among units and introducing consumption costs, a grid evaluation index system including the coordination index of the power transmission and distribution network is constructed. Combining the economic and reliability indicators of the power grid, the power transmission and distribution network planning scheme with the best comprehensive performance is selected through optimization algorithms. To solve the problems of a genetic algorithm being "premature" and easily falling into a local optimum, an optimization algorithm is proposed and applied to the grid planning problem considering the coordination of transmission and distribution network. The simulation results show that the proposed method is feasible and efficient. This work is supported by the National Natural Science Foundation of China (No. 51777142 and No. 51477121) and the National Key Research and Development Program of China (No. 2018YFB0904200).