Machining method of thin-wall internal spline shaft

The invention discloses a machining method of a thin-wall internal spline shaft, which comprises the following operation steps after pretreatment of a machined part: S1, rough turning: when a spline end is machined, enough allowance needs to be reserved for an excircle on which an internal spline is positioned; s2, annealing; s3, semi-finish turning is carried out, the addendum circle of the internal spline is machined, and heat treatment deformation is reserved; s4, outer circle grinding; s5, arranging flower keys; s6, carburizing and quenching; s7, inspection is carried out; and S8, finish turning. By the adoption of the method, enough allowance is reserved for the spline end before carburizing and quenching so as to increase the rigidity of a part, machining stress is eliminated through annealing after rough turning, during semi-finish turning, tolerance is accurately controlled, heat treatment deformation is reserved, an outer circle is ground so as to finish a process datum plane, a spline is arranged, a