As the reflection and coupling of shock wave at the back of specimens reduces residual compressive stress on the surface of titanium alloy thin components,the TC17 Titanium Alloy was processed by the micro-scale laser shock processing(μLSP),and the improvement effect was verified through the high cycle fatigue tests.The improvement reasons of high cycle fatigue performance were analyzed from residual stress distribution and fatigue fracture morphology.The results show that,compared with untreated specimens,the fatigue strength of the specimens treated by μLSP is improved by 32%.Residual compressive stress layer with 100 μm thick and certain values was induced on the surface of the TC17 titanium alloy specimens by μLSP.Under the influence of the residual compressive stress,the crack sources move inward.Simultaneously,there are some fatigue strips and quadric cracks in the propagation zone of the fatigue fractures,and these are the main reasons of the high cycle fatigue performance improvement.