The invention provides a distributed energy storage planning method and system for regional power network peak clipping and valley filling, which comprises the following steps: obtaining power and voltage of energy storage system node; Based on the obtained power and voltage of the energy storage system node, the power, capacity and access position of the distributed energy storage system can be obtained by solving the objective of minimizing the active power loss and voltage fluctuation. Planning based on the power, capacity and access location of the distributed energy storage system. The invention not only calculates the power and capacity of the energy storage system, but also selects a plurality of access nodes of the distributed energy storage, which can not only improve the new energy absorbing capacity of the system, but also reduce the network loss and voltage fluctuation of the power system, and provides a better medium for the convergence of the new energy and the power system.