Energy storage systems play a crucial role in efficient energy programs, as they optimize energy utilization for different types and characteristics of energy sources. This study proposes a gas-CO2 combined energy storage system based on the ideal Ericsson cycle. The system comprises a gas turbine power generation system, a thermal storage system, and a CO2 charging and discharging system. The paper analyzes the effects of storage capacity and pressure ratio on power generation efficiency, energy storage density, and utilization efficiency of flue gas energy. The simulation results demonstrate that integrating energy storage technology with waste heat utilization allows for peak shaving, valley filling, and the consumption of renewable energy. Moreover, it enables the efficient use of high-temperature waste heat from the gas turbine, without harming the environment.