Abstract:Because of the high specific stiffness, the excellent thermal conductivity and thermal stability, Silicon Carbide (SiC) is widely used as the main mirror material of space optical remote sensor. At the same time, it has the characteristics of high hardness and brittleness, resulting in difficulty of mechanical machining and long processing cycle. In this paper, the machining technology of silicon carbide material is analyzed, the advantages and disadvantages of machining technology schemes are compared, and the robot flexible belt grinding is selected at last. Aiming at the requirement of removing the blank ribs of a 1550mm diameter SiC mirror, a new robot soft belt grinding system is built. The stress of the mirror blank in processing is analyzed by using the finite element method, and the removal of the ribs of SiC mirror is completed. The residual height of ribs are between 0.5mm～1mm. After the polishing and coating process, the surface RMS of the mirror is 0.0157λ(λ=632.8 nm), which is measured by the interferometer. The mirror has good performance in orbit, which is launched in 2020.