Abstract: A novel compressed carbon dioxide（CO₂） energy storage system based on gas-liquid phase change was proposed to promote the development of large-scale and high-efficiency energy storage technology. The overall pressure level of the proposed system is lower than the critical pressure of CO₂, which effectively reduces the difficulty of component manufacturing and improves the economic performance of system. Thermodynamic and economic analyses of the system were carried out and results show that the energy storage efficiency of system is 65.35% under typical design conditions and the investment payback period is about 5.50 years. The results of exergy analysis show that the maximum exergy destruction belongs to turbine which is 1.23 MW, and the evaporator has the minimum exergy efficiency which is 9.41%. The results of parameter analysis show that increasing the CO₂ condensation temperature, compressor isentropic efficiency and turbine isentropic efficiency, or decreasing the temperature difference between the cold end and hot end of heat exchanger 2, and the temperature difference between the cold end of heat exchanger 3, can improve the energy storage efficiency and shorten the investment payback period of the proposed system.