To obtain lightweight reflector with high surface accuracy and high reflectivity,SiC was chosen to manufacture reflector,and its preparation process was researched in detail.Firstly,the main design indexes of reflector were proposed on the basis of application requirement for vehiclE-mounted large-diameter fast steering mirror.Then reflector flan was sintered according to lightweight structure of reflector and it was processed to mould by machining.Subsequently the SiC reflector was polishing processed by conventional polishing method after surface modification by physical vapor deposition.Finally,gold reflecting film was coated on the working surface of reflector.After preparation of SiC reflector,its surface accuracy and reflectivity were tested respectively,and the measurement results show that surface accuracy(root-mean-square value) of reflector is less than λ/30,and its reflectivity for medium wavelength laser is about 98%;its reflectivity for long wavelength laser is about 98.2%,which can satisfy application requirements of vehiclE-mounted large-diameter fast steering mirror.