The invention discloses a machining process for a spline shell and relates to the field of preparation of automatic spare parts. The process comprises the steps that firstly, a blank is treated, specifically, A, drilling is conducted, B, the outer diameter is subjected to rough turning, specifically, the front end and the rear end of the blank are subjected to rough turning, and enough cutting allowances are reserved, C, three outside protrusions are milled, specifically, the three protrusions are milled on the outer diameter of the front end of the blank, and D, the outer diameter and the inner diameter of the front end are subjected to finish turning; secondly, the outer diameter is subjected to knurling, specifically, the outer diameter of the rear end of the blank is subjected to outside knurling through a special machine independently; thirdly, finish machining is conducted, specifically, A, the outer diameter is subjected to rough turning, and a rotary groove is turned in the outer diameter, and B, the inner diameter and the outer diameter of the rear end are subjected to finish turning; and fourthly, two key grooves are punched in the inner wall of a shaft hole through a special machine independently.