Yb: LuScO3 crystal is a new type of gain medium used in solid-state lasers. The surface profile and surface quality of the Yb: LuScO3 crystal affect the characteristics of the output laser beam significantly. Therefore, it is extremely important to explore the processing parameters for its ultraprecision optical manufacture. In this paper, a systematic study of the processing parameters for the optical manufacture of Yb: LuScO3 crystal was reported. To solve issues related to the brittleness of the Yb: LuScO3 crystal and the poor quality of the generated surface, the key technology of stitching and the use of copper resin pads were proposed. First, the stress due to different protective paddings was simulated using COMSOL Multiphysics software and the size of abrasive B4C particles was continually decreased during the stitching and lapping stages, respectively. Next, copper resin pads were used during the stage of rough polishing, and their function was explained. Finally, the output power of the continuous wave laser was achieved by diode-pumping the finely polished Yb: LuScO3 crystal. The results reveal a final surface roughness of 0.296 nm (root mean square value) and surface accuracy of 53 nm (peak-to-valley value). An output power of 8.3 W and a slope efficiency of 58% were obtained using a diode laser pump source at a wavelength of 1 086 nm. This method can be widely used for the high-precision machining of Yb: LuScO3 crystals.