Abstract: To promote the development of high-efficiency, large-scale energy storage technology and ensure the balance of supply and demand in the power grid, a low-pressure subcritical compressed carbon dioxide energy storage (CCES) system was proposed, and static and dynamic models were established to analyze the thermodynamic performance and economics during the charging and discharging processes in different operating modes of the system. Results show that the energy storage efficiency under typical operating conditions is 63.37%. The energy consumed during charging process and power generated during discharging process in the steady-state conditions are higher than those in the dynamic simulations, the energy storage efficiency of the system in different modes ranges from 24.86% to 58.65%. Combined with the time-of-use electricity price in Shanghai city, the investment payback period of the system is approximately 5.98-7.45 years, and the isentropic efficiency improvement of the compressor and the expander is conducive to the enhancement of the system energy storage efficiency and the shortening of the investment payback period.