Abstract: This paper tests the fatigue properties of a large-scaled titanium alloy parts, the fluorescent surface quality and fine roots rounded edge position. The most factor for the short performance time is microstructure and fine root fillet by further microstructure examination, micro -hardness determination and fracture surface morphology of macroscopic and microscopic observation and part of the fracture morphology observation under the given stress. The increase of metallographic structure levels obviously improves the fatigue performance. The frontal of the alloy part of the R < 60um fine roots will decrease the fatigue property. It is suggested that the hardness larger than 370. (HVB0.2 B > 370). The direction distribution of process trace has little effect on the service life of the spare parts.