This paper presents the performance analysis of CO2 single door bottle cooler, developed by ITRI, using plate heat exchanger and capillary as gas cooler and throttling device, respectively, in the refrigeration circuit. The power consumption of the CO2 system is compared with that of R134a system as baseline. From the results, it is found that the energy efficiency of CO2 system is higher than that of R134a one by 25% when adjusting the inlet circulation water temperature of gas cooler to 25℃.