Based　on　exergy　analysis　of　charging　and　discharging　processes　in　a　gas-hydrate　cool　storage　system,　the　formulas　for　exergy　efficiency　at　the　sensible　heat　transfer　stage　and　the　phase　change　stage　corresponding　to　gas-hydrate　charging　and　discharging　processes　are　obtained.　Furthermore,　the　overall　exergy　efficiency　expressions　of　charging,　discharging　processes　and　the　thermodynamic　cycle　of　the　gas-hydrate　cool　storage　system　are　obtained.　By　using　the　above　expressions,　the　effects　of　number　of　transfer　units,　the　inlet　temperatures　of　the　cooling　medium　and　the　heating　medium　on　exergy　efficiencies　of　the　gas-hydrate　cool　storage　system　are　emphatically　analyzed.　The　research　results　can　be　directly　used　to　evaluate　the　performance　of　gas-hydrate　cool　storage　systems　and　design　more　efficient　energy　systems　by　reducing　the　sources　of　inefficiency　in　gas-hydrate　cool　storage　systems.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.