The invention discloses a dual-temperature refrigeration cycle system used for fractional condensation of non-azeotropic mixed refrigerants and capable of improving the effect by adopting an ejector. High-temperature and high-pressure non-azeotropic mixed refrigerants discharged from a compressor are cooled by a condenser I to form a refrigerant in a gas and liquid double-phase state; the refrigerant in the gas and liquid double-phase state is divided into two channels in a gas and liquid separator, wherein one channel is characterized in that a saturated gas refrigerant rich in a low-boiling-point refrigerant is cooled into a saturated solution by a condenser II, overcooled by a reheating machine, throttled by a freezing capillary tube and treated by a freezing evaporator to become a saturated gaseous refrigerant; the other channel is characterized in that a saturated liquid refrigerant rich in a high-boiling-point refrigerant enters the ejector after sequentially passing through a refrigeration capillary tube, a refrigeration evaporator and a main flow inlet of the ejector; the ejector is used for ejecting the saturated gaseous refrigerant rich in the low-boiling-point refrigerant from the freezing evaporator; the two channels of fluid is mixed and pressurized in the ejector and is then discharged from the ejector; and the fluid becomes overheated gas after passing through the reheating machine and finally enters the compressor to realize a complete refrigeration cycle. The dual-temperature refrigeration cycle system disclosed by the invention has the advantages of reducing the power consumption of the compressor and effectively improving the performances of a refrigeration system.