The embodiment of the utility model provides a prevent that low temperature freezes oil from cascade refrigeration system relates to the refrigeration technology field, can solve lubricating oil and get into the interior stifled problem of lubricating oil ice that forms of evaporimeter unit through middle regenerator. This system includes compression refrigeration device, middle regenerator and first throttle unit and evaporimeter unit, the thermal current entry of middle regenerator exports the entry through first throttle unit connection to evaporimeter unit through the first exit linkage of pipeline with the compression refrigeration device, the thermal current of middle regenerator, the first cold flow entry of middle regenerator communicates through the export of pipeline with the evaporimeter unit, and the cold flow export of middle regenerator is through the entry linkage of pipeline with the compression refrigeration device, the second export of compression refrigeration device is through the second cold flow entry intercommunication of noncongeable oil unit with middle regenerator, behind the system start -up, the noncongeable oil unit is opened and is got into two -way on -state, after the system closed, the unidirectional flux state that gets into was closed to the noncongeable oil unit.