Analyzed the shortcoming of traditional grooved mirror used on the ring laser gyro (RLG) about its masterial and structure, a new structure of grooved mirror was designed, which syncretized the advantanges of both of glass-ceramic (zerodur) and fused quartz. The body of the mirror is made of glass-ceramic, the same material of the gyro block. The reflective stice is made of fused quartz, whose surface can be polished to higher quality. These two components are combined to become the new mirror. Accordingly a new method was put forward to machine the gyro block surface on which the grooved mirror fixed. It can make the block to suit to the new mirror without more difficulties. A new method was also put forward to polish the substrate and the spherical surface of the mirror separately. Not only has it resolved the problem that the helium leaks through the fused silica material, but also reduced the difficulties is superpolishing the surface of the mirror's substrate.