The invention relates to a non-combustible mixing refrigerant suitable for deep refrigeration temperature of minus 80 DEG C to minus 100 DEG C. The non-combustible mixing refrigerant comprises five groups of materials, where the first group of material is tetrafluoromethane; the second group of material is trifluoromethane, hexafluoroethane or a mixture of the trifluoromethane and the hexafluoroethane; the third group of material is pentafluoroethane, trifluoroethane, perfluoropropane, difluoromethane or a mixture of two, three or multiple of the pentafluoroethane, the trifluoroethane, the perfluoropropane and the difluoromethane; the fourth group of material is iodotrifluoromethane, 1, 1, 2, 2-tetrafluoroethane, 1,1-difluoroethane, 2, 3, 3, 3-tetrafluoropropene, 1, 3, 3, 3-tetrafluoropropene or a mixture of two, three or multiple of the iodotrifluoromethane, the 1, 1, 2, 2-tetrafluoroethane, the 1,1-difluoroethane, the 2, 3, 3, 3-tetrafluoropropene and the 1, 3, 3, 3-tetrafluoropropene; the fifth group of material is perfluoro-n-butane, 1, 1, 1, 3, 3-perfluoropropane or a mixture of the perfluoro-n-butane and the 1, 1, 1, 3, 3-perfluoropropane; the molar concentrations of the five groups of materials are respectively 25-50%, 15-40%, 10-30%, 5-20% and 10-25%; and the non-combustible mixing refrigerant is safe in a back-heating type throttling refrigeration system, can realize the refrigeration in the temperature range of minus 80 DEG C to minus 100 DEG C and has low whole green house effect without ozone depletion effect.