In this paper, we analyze the mechanical characteristics of a hyperstatic and hyperstable spacecraft structure integrated with a satellite load platform. The current challenge with this type of large-size flexible structure is designing for frequency and addressing thermal deformation on the celestial surface in a complex high orbit temperature field environment. In the past, ground tests were primarily used to verify the theory and methods of structural design to overcome these issues. In this study, we conduct co-simulation of thermal deformation and micro-excitation on the spacecraft structure. By inputting load spectrum data under different temperature conditions, we obtain the output under the co-simulation condition. The results indicate that the thermal field has minimal impact on the attenuation of axial force transmission characteristics. Furthermore, compared to a single field analysis, the mechanical properties of force-heat under micro-excitation exhibit less attenuation.