Abstract: With more and more research being carried out to replace CFC and HCFC,some new green-refrigerant fluids are obtained,but those fluids are only used in some fixed-temperature fields,it limits the used in a bigger range of variable performance.According to this situation,theory etical and experimentsal’ conclusions are drawn in order to solve this problem in the paper.Non-azeotropic mixtures have temperature-gliding in phase change.CSD equation of state is used for theoretical calculation.Some mixtures that may be used in a bigger range of variable perfomance are found.Experiments are carried out in a refrigerant system.The mixtures S3 is recommended.