The temperature guarantee system of the ring mold equipment of the cryogenic unit with compound working fluid is mainly composed of cryogenic unit, heat sink and heating cage. The cryogenic unit cools the heat sink in the vacuum chamber to obtain the low temperature background. By adjusting the output power of the heating power supply of the heating cage, the temperature range of - 140 ℃ ~ + 150 ℃ can be obtained in the vacuum chamber. This refrigeration method is suitable for small and medium-sized ring mold equipment with moderate temperature range.