Abstract: Since the salt cavern gas storage was constructed in China, diesel blanket has always been used to control the cavern shape, which is costly and polluting. Therefore, nitrogen blanket is proposed for the leaching of cavern. However, as the nitrogen is easy to leak and has strong compressibility, and it is difficult to control the gas-water interface, the solution-mining-under-nitrogen technology was developed by reforming the flow of wellhead, developing the associated field nitrogen injection equipment and establishing the monitoring and control system of gas-water interface, and for the technology, field tests were carried out. As indicated in the tests, nitrogen can be used as the blanket material for solution mining of salt-cavern gas storage, with good effects and the gas-water interface can be controlled effectively. Further, the control method of gas-water interface with nitrogen blanket was developed for cavity roofs with different opening, and valuable field experience was accumulated for the solution-mining-under-nitrogen technology.