The performances of an air-conditioning system with R22/R114 refrigerant mixture of 60,80 and 100 mol % R22 respectively as the working fluid were tested. The COP for the mixtures was found to be higher than that for pure refrigerant, and a molar fraction of 70%∼80% R22 for the mixture seemed to be more favorable. Analysis of the experimental data showed that it was necessary to optimize the heat transfer areas of the condenser and evaporator in an air-conditioner before using the mixture in practice. Since the 1960s, non-azeotropic refrigerant mixtures (NARMs) have gained expensive interest as the working fluid of a vapour compression heat pump and refrigeration plant system Experimental and theoretical studies [1−4] on heat pumps and refrigeration plants with NARMs have been made by more and more departments presently. In this paper, experimental investigations have been made in an air conditioning system with binary non-azeotropic refrigerant mixture R22/R114, performance data and the application of NARMs cycles were obtained, and prospect of air conditioner using NARMs as refrigerant was discussed.