The invention relates to a machining technology for a precipitation hardening stainless steel pump shaft. The machining technology includes the following steps of forging, rough turning I, UT detection, heat treatment, rough turning II, high-temperature aging, semi-finish turning I, semi-finish turning II, low-temperature aging, coping and lapping, finish turning I, grinding I, lineation, milling,grinding II, flaw detection, chromium plating, dehydrogenation treatment, chromium plating removing protection, grinding III, grinding IV, finishing and finish product obtaining. By means of the machining technology for the pump shaft, the machining hardening effect is small, size deformation is small, the pump shaft machining size precision is good, the surface smoothness is high, and the finishing size inspection is controlled to be below 40 DEG C; and in addition, the machining efficiency is high, the quality is good, it can be ensured that the size precision and the shape and position dimensional tolerance deformation of the pump shaft are small, and drawing size requirements and technical requirements are met.