Abstract: In order to study SiC crystal application in optics,the grating structures on the surface and inside of SiC crystals were fabricated using femtosecond laser cold processing method,respectively.The effect of femtosecond laser power density and scanning speeds was studied in detail.Finally,the gratings were fabricated under appropriate processing conditions.After that the gratings period was verified in the diffraction experiments and the diffraction angles at different orders were calculated,the gratings were annealed at 1300℃,the grating parameters had no obvious change after annealing.It indicates that the fabricated gratings in SiC can be applied in high temperature environment.