As a carrier of the optical elements in a space camera, the main supporting structure of the space camera plays a decisive role in making the relative positions of optical elements accurate and stable for a long time. Because of the advantages of high specific stiffness and high thermal stability, high volume SiC_p/Al composites are very suitable for making opto-mechanical structures for space application. Since the ultrasonic-aided brazing technique can solve the welding problem of high volume SiC_p/All composites, it has laid a foundation for the application of high volume SiC_p/Al composites in the main supporting structures of space cameras. A main supporting structure for a certain space camera based on high volume SiC_p/Al composites is presented. The mechanical properties of two similar main supporting structures made of TC4 and high volume SiC_p/Al composites respectively are analyzed. The results show that the weight of the main supporting structure made of high volume SiC_p/Al composites decreases by 31.8% and the first-order frequency increases by 25%. It is known in the mechanical and thermal tests that the main supporting structure meets the requirements in weld strength and size stability.