The invention provides a mixed refrigerant. The mixed refrigerant comprises trifluoroiodomethane, fluoroethane, a third component and a fourth component. The third component comprises 1,1-difluoroethane and / or 1,1,1,2-tetrafluoroethane. The fourth component is selected from one or more of trans-1,3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene, carbon dioxide, propylene, dimethyl ether, difluoromethane, monofluoromethane and isobutane. The fourth component is obtained by compounding the trifluoroiodomethane and the fluoroethane with the 1,1-difluoroethane and / or the 1,1,1,2-tetrafluoroethane. The GWP (global warming potential) of the mixed refrigerant is greatly reduced, and GWP requirements of automotive air conditioner refrigerants are met.