Abstract: To verify the effect on accuracy of star sensors by deformation of the bracket of star sensors in space, structure stability and thermal stability of the bracket were investigated. Structural properties of the bracket were analyzed by FEM and then the temperature data in worst case on orbit were mapped to the structure model. Based on the temperature data, the thermal deformation of bracket was figured out and vectors of optic axes of star sensors were obtained by least square method. Finally experiment was conducted to verify the analysis. Results indicated that fundamental frequency of star sensors and the bracket was 429 Hz with the difference less than 2% from the analysis and the max variety of the optical axes after vibration test was no more than 5. The max temperature change of the bracket in orbit was less than 2 ℃ and the max variety of the optical axes was about 4-5 which was similar to the analysis. Both the ground test data and orbit data demonstrate that the bracket of star sensors has good structure stability and thermal stability which can meet the requirement.