In order to assess the equivalent capacity of new energy storage in provincial power system, this paper forecasts the power demand, power supply scale and structure, and the development of the new energy storage in provincial power system in the middle and late stages of the Fourteenth Five-Year Plan. It is the first time to use 5-minute power data to carry out production simulation analysis, and analyze the profit and loss distribution of power and electricity on the summer heavy load day, which breaks through the defects of the conventional power production simulation for the hourly analysis. In this paper, according to the new energy storage operating hours of 2 hours, AC side efficiency of not less than 85% of the way to measure, in 2024, 2025, the province respectively configured a new energy storage 7.15 million, 11.09 million kilowatts, the day of the discharge of electricity only accounted for the province's power shortfall of 45%, 35%. Therefore, only rely on new energy storage cannot completely solve the problem of power supply, the province needs to synergize its efforts in the source-network-load-storage to enhance system stability.