Energy storage can alleviate network congestion through "charge in low load period and discharge in high load period", and solve the contradiction between the difficulty of power grid construction and the requirement of reliable power supply. However, there are few researches on optimization of energy storage planning to alleviate network congestion and reasonable alternatives to traditional power grid investment.Therefore, this paper proposed an optimization method of energy storage planning for alleviating network congestion. Firstly, the load center network section is divided by using the principle of layering and partitioning. Secondly, the energy storage planning optimization model that comprehensively considers energy storage investment and maintenance costs, system congestion costs, and energy storage charging and discharging benefits is constructed, and the model solution method is proposed with particle swarm algorithm. Finally, a simulation is carried out with a load center in the Guangdong-Hong Kong-Macao Greater Bay Area to verify the feasibility and effectiveness of the model and provide a reference for power grid planning.