Auto-cascade refrigeration system and low-temperature cabinet

The invention discloses an auto-cascade refrigeration system and a low-temperature cabinet. The auto-cascade refrigeration system comprises an auto-cascade refrigeration loop and a control system, wherein the auto-cascade refrigeration loop is formed by connecting a compressor, an oil separator, a condenser, a multi-stage gas-liquid separator, a multi-stage heat exchanger, a heat regenerator and an evaporator through a refrigerant liquid path and a refrigerant gas path; the expansion tank is connected to the refrigerant gas path and used for relieving pressure of the system, a connector part communicated with the inner space of the expansion tank is formed in the bottom of the expansion tank, and the air suction side of the compressor is connected with the connector part through a compressor air suction channel. According to the invention, the problem of difficult oil return of the compressor in the auto-cascade system in the prior art is solved. 本发明公开了一种自复叠制冷系统及低温柜，自复叠制冷系统包括有：自复叠制冷回路：其由压缩机、油分离器、冷凝器、多级气液分离器、多