Abstract: Based on the thermal analysis module of ANSYS, two finite element models were established respectively on the structure of main-vice reflector and the structure of bar system. The boundary conditions of periodic air temperature, solar radiation, long-wave radiation and shadow of the surrounding environment were computed each half hour in a cloudless day (July 15th) in summer as one of the worst-case weather conditions. The distribution of temperature field was obtained and analyzed on main-vice reflector, especially on a phenomenon called “solar cooker” caused by the solar radiation energy which is reflected and converged on the vice reflector, and this phenomenon makes the temperature of vice reflector increase sharply. Simultaneously, in order to find out the changing law of the pointing error of radio telescope in the environment of sun exposure, an analysis was made on non-uniform thermal deformation of the bar system. The relation between surface precision and time was given in the form of curve-line graph. The results show that the phenomenon called “solar cooker” increases the temperature of vice reflector to as high as 135℃; due to the non-uniform temperature field under exposure, the highest temperature difference in the structure of bar system reaches 10.8℃. The existing of sun exposure and shadowed face results in non-uniform thermal deformation of the main reflector, which makes RMS (Root Mean Square) increase as large as 0.35mm when the pitch angle is 90°. The data provide valuable reference for the construction, sensor arrangement and local temperature control of radio telescope.