Abstract: Using carbon dioxide as cushion gas for natural gas storage can not only save the deposition capital, but also realize carbon sequestration storage and reduce greenhouse effect. It is a choice that can "hit two hawks with one stone" for the development of natural gas industry and the environment problem as the result of generating electricity by firepower in China. According to the research on reduce the discharge rate of carbon dioxide to atmosphere and the thermo-property of carbon dioxide, this paper gave the feasibility of using carbon dioxide as cushion gas for natural gas storage and the best thermodynamic conditions of using carbon dioxide as cushion gas. Therefore, it provides the theoretic basis for realizing carbon sequestration storage and establishment and running of gas storage in China.