When the linear damage accumulation theory was used for study on shaft structural fatigue of machine tool, since the relationship between damage and load was unable to be described continuously, the calculation result in high cycle fatigue life prediction is not satisfactory. Therefore, based on the no-linear continuum damage accumulation theory presented by CHABOCHE, a multiaxial non-linear continuum damage accumulation model suitable for shaft structural fatigue life prediction of machine tool was established, according to the shaft structural material S-N curve obtained from steel No. 45 fatigue test and based on the simplification of cyclic load spectrum of machine tool. The calculation in particle example proves that the model can accurately describe the damage accumulation process of shaft structure of machine tool, and gives a result meeting practice projects.