Abstract: After salt-cavern gas storages are completed, diesel oil can't be used as the blanket for re-leaching solution mining of deformed caverns, so it is in urgent need to develop the re-leaching solution mining technology under natural gas. In this paper, the process flow, process parameters and cavern building simulation technology of this new technology were investigated and tested on site in Jintan Gas Storage of West-to-East Gas Pipeline. The test results are better than the expectations. The free volume of the cavern A increases by 14 000 m³. And besides, the prominent rock ridge at the upper part of cavern A collapsed naturally, so the damage risk of the falling salt rocks on brine displacement strings in the later gas injection de-brining stage was eliminated. This test is the first salt cavern expansion and repair test in China. It is of great engineering guiding significance to the popularization of salt cavern building technologies and the reduction of cavern building cost in the future.