Abstract: In order to solve the deformation problem of the slender pump shaft in the machining process, the heat treatment process of the forging material of the pump shaft was improved, and the stabilization heat treatment process was added. The mechanical properties analysis, metallographic analysis, residual austenite content analysis and residual stress analysis of pump shaft materials before and after process improvement were carried out. The results show that the improved process reduces the internal stress of raw materials and the pump shaft deformation caused by the release of internal stress during processing. Thus,the surface runout of pump shaft after machining is reduced, and the qualified rate of pump shaft processing is improved.