Abstract: To enhance the anti-risk capability of the high-value large communications satellite under extreme thermal conditions, and with some deviation from the selected working procedure, this paper analyze the platform temperature distributions in the geostationary transfer orbit(GTO) in five typical states, namely, the fairing jettisoning, the SC/LV separation, the exiting from the Earth’s shadow, the +y board under illumination, and the -y board under illumination. The thermal analysis result shows that the temperature of the platform is from 51.68 ℃ to-16.35 ℃, well within the required temperature limit, which demonstrates that the platform has an adequate ability to keep its temperature condition, but the margin between the temperature of the platform body and the thermal control requirements is only between 3.3 ℃ and 3.6 ℃, which should be paid attention to. At the same time, the finite element analysis method with 3D cabin reveals that the maximum thermal gradient in the direction of the thickness of the service cabin is 5 ℃at the time of exit from the ground shadow, which may bring potential risks with regard to the structural accuracy and the kinematic performance of the mechanism.