Abstract: As a large number of photovoltaic units are connected to the distribution network, it is necessary to maintain voltage stability of the power system while increasing the use of intermittent renewable energy. Rapid advances in energy storage technology allow the deployment of energy storage systems to support voltage regulation. To achieve the dual optimization of network losses and the cost of voltage regulation measures in a PV energy storage optimized power system,an improved Pareto archival particle swarm multiobjective optimization algorithm is proposed in this paper. The Niche technique is added to the calculation of the congestion distance in the non-dominated ranking link to avoid falling into a local optimum while increasing the diversity of the Pareto solution set distribution. The proposed PV-ESS（photovoltaic energy storage system） optimization method is tested based on the IEEE 30 distribution grid system. The results demonstrate that the algorithm performs well in suppressing light fluctuations,improving voltage stability and reducing network losses,which in turn maintains the stability of system operation and reduces the cost of voltage regulation measures and power industry costs.