The low temperature screw cascade unit consists of two or more independent refrigeration cycles, called high temperature cycle and low temperature cycle. Each individual refrigeration system is filled with a refrigerant of a different nature. The high temperature cycle usually uses a medium temperature refrigerant, and the low temperature cycle usually uses a low temperature refrigerant. A single-stage or two-stage compression refrigeration cycle can be used for each cycle. These two parts are connected by a condensing evaporator, which is a low-temperature circulating condenser, which is also a high-temperature circulating evaporator, that is, the evaporation of the refrigerant in the high-temperature cycle is used to condense the refrigerant in the low-temperature cycle. Thus, the heat (cooling capacity) absorbed by the low-temperature cycle is transmitted to the high-temperature circulating refrigerant, and the high-temperature circulating refrigerant transfers the heat to the environmental medium.