Abstract: In this article, a method that can solve the problems of thermal design of the pipe that was suitable for the characteristics of space environment of the Mars Probe was proposed. By adopting optimized heating power, suitable number of layers and suitable zone of the heaters, thermal control of the pipeline under complex external heat flow was realized. In the design of propulsion pipeline of Tianwen-1 Mars Orbiter, this method was analyzed and verified, and influencing factors, such as the change of ambient temperature, whether the propulsion pipeline had working fluid, whether it was exposed to the sun, the number of coating layers and heating power, were also analyzed. Research shows that this method had high adaptability to the environment and could adapt to the whole process of the orbiter flight and the conditions of orbit change; more attention should be paid to the number of coating layers and heating power in the future; the extravehicular pipeline was greatly affected by sunlight, exposure to sunlight should be avoided as much as possible in the design process. The research findings above can provide some reference for thermal control design of the propulsion pipeline in subsequent deep space explorations.