Abstract: The fatigue properties of TC17 titanium alloy circular perforated plate specimens were different. The reason for the differences was analyzed by scanning electron microscopy and energy spectrum analysis, metallographic examination, residual stress test and roughness test. The results show that for the plate-shaped circular hole fatigue specimen with K_t=2.52 and short life, the fatigue crack originated from the processing damage at the rounding of the hole edge or the processing damage of the inner wall of the hole, and the fatigue cracks of the longer life specimen originated from the inner wall of the hole. For the plate-shaped hole fatigue specimen with K_t=2.1 and short life, the fatigue crack originated from the machining damage of the inner wall of the hole or the rounding damage of the hole edge, while the fatigue cracks of the long-life specimen mostly originated from the surface machining defects or the subsurface of the inner wall of the hole. The fatigue properties of the samples were greatly different due to the processing damage of the samples, the large residual compressive stress on the inner wall of the hole and the dispersion of the residual stress.