Abstract: The cavity damage evaluation is one of the important problems involved in safe operation of salt-cavern gas storage. By virtue of damage mechanics, rock rheology theory and finite element numerical simulation, the evaluation system of cavity damage during the operation of salt-cavern gas storage was investigated by performing laboratory system tests on the mechanical properties of salt rocks. The methods for evaluating salt rock damage include maximum tensile stress criterion, maximum shear stress criterion, maximum distortional energy criterion, expansion strength criterion and creep strength criterion. The evaluation index of the concerned salt caverns was numerically simulated and calculated using ABAQUS software, and the calculation results were compared with the measured sonar values. It is shown that the cavity damage evaluation system adopted in this paper can be well used to evaluate the damage in the process of gas injection and withdraw, and it provides the basis for the assessment, prediction and control of salt rock damage in the future.