The invention discloses an energy-saving ultralow-temperature preservation box which comprises a high-temperature refrigerating cycle unit and a low-temperature refrigerating cycle unit. The high-temperature refrigerating cycle unit and the low-temperature refrigerating cycle unit are coupled together by a
heat exchanger; the high-temperature refrigerating cycle unit comprises a cycle compressor, a condenser, a first
drying filter, a first capillary tube, a first
automatic control valve component and a second capillary tube; and the low-temperature refrigerating cycle unit comprises a low-temperature compressor, an oil separator, a first heat regenerator, a second heat regenerator, a first
drying filter,, a second
drying filter, a third capillary tube, a second capillary tube, a first,
automatic control valve component, a second
automatic control valve component, a third automatic control valve component, a fourth automatic control valve component, a fifth automatic control valve component and an
evaporator. The high-temperature refrigerating cycle and the low-temperature refrigerating cycle are coupled to realize low-temperature
refrigeration, and the heat regenerating cycle form and the capillary tube energy-saving cycle form are used to improve the regenerating
cycle efficiency. The energy-saving ultralow-temperature preservation box has the characteristics of high temperature decreasing speed, high regenerating efficiency, safety, reliability, energy saving and environment friendliness and can meet the regenerating requirement of the low-temperature environment of 50-90 DEG C below zero.