This study discusses the influence of temperature on infrared optical system and introduced the principle and method of non-thermal design. Based on the requirements of orbital thermal environment and technical indexes of a space-based infrared imaging system, this study conducts the thermal environment adaptability design of an imaging system. The nonthermal design of the optical system is carried out by combining active and passive methods, and thermal design and thermal analysis are carried out for the thermal environment of space orbit in which the system works. Finally, the final imaging system is validated by the thermal imaging experiment. The experimental results show that the system can eliminate the influence of temperature change on image quality in the temperature range of-20 ~ + 50 ℃, and can adapt to the thermal environment of space orbit. The imaging quality can meet the application requirements under different temperature conditions.