A transmission-type cryogenic optical infrared camera works in IGSO, the space thermal environment of which is complex and changeable. As a part of the cryogenic optical system, the all-optical path needs the high requirements of temperature gradient and temperature stability, which brings challenges to the design of thermal control system. The key points and difficulties in the thermal control design of camera were analyzed in detail according to the temperature requirements of the camera in orbit and the characteristics of the heat flow outside the space. The cooling process of cryogenic optical system was realized by the heat transfer of low-temperature heat pipe and the radiative cooling, and the high-precision temperature control of the cryogenic optical system was realized through the high-efficiency thermal protection, thermal isolation and indirect radiation temperature control technology. The results of thermal balance test show that the temperature of each optical component all meets the requirements, and the temperature uniformity and stability of the optical lens are high under the imaging case. The maximum temperature difference between the optical lenses is less than 1 K, and the maximum temperature fluctuation is less than ±0.3 K. High precision temperature control of optical lens in complex internal and external thermal environment is realized. In the heating decontamination case, the thermal resistance of the low-temperature heat pipe is increased at room temperature by using the characteristic of “thermal switch” for the low-temperature heat pipe, and the requirement of heating decontamination of optical lens can be realized through small control power consumption.