Abstract: Pressure, as an important parameter for the startup and operation of high-power spaceborne products, can affect the damage and in orbit lifespan of the products. Due to the temperature rise of high-power products on board the satellite after startup, pressure rebound may occur during component deflation, posing a safety hazard to the product. This article starts with the study of the relationship between the diffusion concentration of gas inside the material and temperature changes. Based on the increase in material desorption gas caused by the temperature rise after the power supply of a certain space borne product is turned on, different baking temperatures, baking times, and scenarios are used as boundary conditions to calculate the internal pressure changes of the product before and after turning on under molecular flow conditions, and numerical simulations are conducted. This article provides a theoretical basis for predicting the pressure changes during startup operation and designing exhaust ports in the space environment of microsatellite products.