Abstract: As more and more underground gas storages (UGS) are put into production in the world, the safe operation and injection/production capacity of underground gas storages has gradually become the focus of attention. In this paper, UGS injection and production reliability was studied by using multiple methods comprehensively (e.g. Monte Carlo method and K/N redundancy system) combined with reliability and UGS operation theories. The research included the establishment of UGS system evaluation index, the calculation of UGS system reliability, the simplification and calculation of UGS injection and production process, and the establishment of reliability calculation model on main units which affect UGS injection and production capacity. Finally, the research results were applied to a certain UGS injection and production process to calculate its reliability of equipment, units and system. It is indicated that the results can reflect how the injection and production reliability of UGS equipment units and system varies with the change of the process parameters and the running time. The research results are of great engineering significance to guide UGS reasonable and safe operation and improve UGS injection and production capacity.