It is difficult to process a long and slender shaft on a lathe. Generally, a long lathe bed and a plurality of center frames are required to support the workpiece, and a certain level of technology is required. Through practical exploration and reform, we have developed a slender shaft cutting disc that is mounted on a C616 lathe to produce an infinitely long slender shaft. During machining, the workpiece does not rotate, only the axial movement, the cutting disc rotates at a high speed, and the double cutter simultaneously cuts. The machining accuracy can reach IT8, the surface roughness is R_α0.8, and the full-length outer diameter size error does not exceed 0.53mm.