Abstract: As salt rock is a typical rheological material, creep property has a significant influence on stability of the underground storage, and the reliability has strong time-variant property. Although much work had been done on the mechanical property and deformation characteristic of salt rock, utilizing stochastic mechanical theory in time-variant reliability risk analysis of salt rock storage was scarcely published all over the world. The reliability function is established to calculate the time-variant reliability and analyze the risk of an underground salt rock gas storage in China. Taking volumetric shrinkage as a risk controlling criterion, and adopting response surface and Monte Carlo methods, creep stochastic mechanical calculations under different intrinsic pressures have been done on the storage during service period; laws of reliability index with time and risk level are obtained; and the equation between volumetric shrinkage limitation within reliability requirements and intrinsic pressure of the storage is fitted. Major random parameters sensitivity to reliability index are further discussed. Some useful conclusions are finally obtained, which could provide scientific basis for the storage safety operation and maintenance

Key words: salt rock storage, creep, stochastic mechanics, time-variant reliability, risk, volumetric shrinkage limitation, numerical simulation