Photovoltaic energy storage configuration is the current development trend, but the value of energy storage investment directly affects the interests of energy storage owners and the actual market behavior, it is necessary to consider the interaction between energy storage benefits and costs, and carry out further research on the basis of traditional multi-objective optimization of the grid side or the maximum economic benefit of energy storage. Therefore, a two-layer optimal configuration model of distribution network energy storage with distributed photovoltaic, which adopts multi-objective particle swarm optimization and considers the optimal marginal benefit. Firstly, the concept of marginal benefit of energy storage is put forward, the marginal benefit model of energy storage is established, and the benefit of energy storage is measured from the perspective of energy storage owners. Then, a two-layer optimization model is established. The outer layer optimization takes the maximum marginal benefit and the minimum voltage deviation after energy storage access as the target, and takes the network loss rate as the constraint condition. The inner layer optimization takes the maximum daily energy storage income as the target to optimize the energy storage output. Finally, the IEEE 33-node system is used for energy storage optimization calculation. The results show that on the basis of traditional energy storage capacity optimization with net income over the whole life cycle, based on the optimal marginal benefit of the energy storage owner, the secondary allocation of energy storage capacity with the goal of considering marginal benefit and voltage deviation can improve the net income, line loss rate and voltage deviation after energy storage access.