For internal curved surfaces with multilateral and internally square, multi(or single) keyways uniformly distributed, they are usually slotted by using general slotting machines. Owing to low precision of slotting machines and inaccurate positioning of slotting tools, it is hard to guarantee the size and positional accuracy of internal curved surfaces with high precision and leads to low manufacturing efficiency. Based on the principle and functional characteristics of CNC gear shaping machines, the research of slotting on multilateral and internally square, multi(or single) keyways performed by CNC gear shaping machines instead of general slotting machines was focused on.The practice shows that the slotting technology of internal curved surfaces performed by CNC shaping machines is applicable and manufacture quality is stable. Since it is a technology with high maturity and distinguished efficiency, it is of great value to use publically and extensively.