Abstract: For improving the antenna’s performance, it is essential to accurately predict the antenna’s on-orbit temperature and analyze the factors affecting the antenna’s thermal stability. A finite element model is established for simulating the temperature field and the thermal deformation of a mesh antenna. With this model, the temperature field and the thermal deformation on the carbon fiber main reflecting surface, the support rib assembly and other mechanisms are determined under the conditions of the side solar incidence with two levels of irradiance. And in the vacuum and in the low temperature environment, the solar simulator is used to test the thermal deformation of the mesh antenna. It is found that the calculated results based on the simulation model are in good agreement with the experimental measurement results. Because the collimation of the heat flow has a significant influence on the experimental results, the radiation error compensation should be made in the thermal simulation according to the collimation of the incident heat flow.