Abstract: Designing and developing more underground salt cavity storage projects are one of the trends of the natural gas storage in 21 century. Because the present technology is that 40% to 50% of total amount of gas stored must stay in the cavity to provide the pressure necessary to deliver the rest, which will result in more cost and the increasing of difficulty and complexity in operation. However the alternative cushion gas technology can overcome the shortcomings of the older technology. In this article, firstly the theory of the new technology are described, then the practical use of alternative cushion gas in salt cavity storage specially, such as selection of materials, and practicing the technology, and technology process and study of failsafe requirements, are discussed. At last, the advantages of the new technology in contrast of the older one in technology and engineering aspects are illustrated. By contrasting and analysis, the paper considered that it is very necessary to develop more study in the technology, if this technology put into application in China as soon as possible, it will reduce the project cost and convenient to the operation of the salt cavity storage.