C/SiC composite material was applied to design of secondary mirror bearing cylinder in large aperture space telescope. Firstly, the material characteristics of C/SiC composite material and the applications in space optical remote sensor were introduced. Secondly, taking secondary mirror bearing cylinder of a large aperture space telescope as an example, the weight and structural-thermal performance based on different materials were compared. The analysis results indicate that C/SiC reduces the weight of secondary mirror bearing cylinder to 32 kg by 45.5% compared with titanium alloy cylinder. With natural frequency of 204 Hz, the structure meets the design requirement and can control the influence of thermal deformation on the shape of mirror. Finally, the C/SiC secondary mirror bearing cylinder was developed and the main physical properties were tested, and the mechanical vibration test was carried out, and the three-coordinate measurement data of the structure before and after vibration were compared. The results show that the fundamental frequency is excellent. Moreover, the frequency drift is less than 1% before and after the vibration test, and the micro displacement of the structure is in micron level. This paper provides several reference value for the design of large size integral bearing structure of space remote sensor by using C/SiC.