The invention relates to a machining process of a hollow transmission shaft. The machining process comprises the steps of material preparation, rough turning, heat treatment, finish turning, aging, clamping, D-D section key slot line lineation, milling, outer circular grinding, thread milling, spline rolling, two tip positioning, spline rolling and turning as shown in picture, inner circular grinding, turning, end tooth grinding, clamping, turning, magnetic detection and dynamic balance of modules. In general, the machining process has the advantages of improving the working efficiency, the machining performances and the workpiece size precision.