The invention provides a mixed refrigerant refrigeration circulating system which comprises a compressor, a generator, a first condenser, a first heat exchanger, a throttling valve, an evaporator, an injector, a second condenser, a liquid-vapor separator and a driving pump. Mixed refrigerant passes the compressor to enter the generator, the condensers and the heat exchanger, and then enters the heat exchanger to be reheated prior to be injected by the injector; after being mixed with the injected refrigerant, the mixed refrigerant enters the condensers to turn into vapor and liquid phases, and after being separated via the liquid-vapor separator, the vapor-phase refrigerant enters the compressor; the liquid-phase refrigerant passes the driving pump and the generator, then flows into the injector prior to injecting the vapor-phase refrigerant reheated by the heat exchanger, and finally is mixed in the injector prior to entering condensers, and accordingly circulation is finished. The mixed refrigerant refrigeration circulating system has the advantages that the compressor is used for heat remove, high-temperature and high-pressure steam is generated to drive the injector to inject throttled refrigerant, suction pressure of the compressor is raised, back pressure is increased, and efficient low-temperature refrigeration is achieved.