Abstract: Taking tiny narrow groove as the research object, the structure characteristics of Inner Core workpiece are introduced. The machining difficulties of the workpiece were analyzed from the aspects of turning vibration and taper, tiny narrow groove turning, turning surface quality and programming efficiency. A reasonable numerical control turning process has been worked out. A special turning tool for tiny narrow groove was designed based on the structure of separated replaceable tool head. On the premise of ensuring the rigidity of the tool, the geometric Angle of the tool was determined through three factors orthogonal test, and the special turning tool was prepared. Reasonable cutting fluid was chosen to improve the surface quality of the machined surface. Method of macroprogram was applied to finish NC program efficiently, which has simplified the machining program and improved the production efficiency.