Salt rock is internationally recognized as the most ideal energy underground storage medium because of its good creep properties，low permeability and damage recovery characteristics. Casing structure of gas storage in underground salt rock is affected by internal pressure

material parameters and geometric size of casing which are uncertain during the operation process of gas storage. In order to evaluate effects of these random risk factors on operation safety of casing structure

a mechanical model and the structure function of casing based on Von Mises yield criterion have been established. According to the established mechanical model and structure function

the change laws of reliability of gas storage casing under the high pressure and low pressure conditions are obtained through the response surface combined with Monte Carlo sampling. Reliability analysis shows that the minimum operating pressure of gas storage should be greater than 3 MPa

the maximum operating pressure of gas storage should be less than 22 MPa

the distance between the casing shoe and the gas storage cavity should be more than 10 m. In order to ensure the safety operation of the gas storage casing

it is very important to appropriately increase the casing wall thickness and decrease the diameter of casing.