TC17 titanium alloy was laser peening (LP) processed by different power densities.X-ray diffraction method was used to measure the residual stress induced by LP.Vacuum thermal retardation at 280℃ and 450℃ for 160min was used to study the residual stress relaxation regularity.The prediction model was based on support vector machines (SVM) theory and the model was verified by experimental results at last.The results show that 4GW/cm2 is the optimal power density to process TC17 titanium alloy.The thermal relaxation is about 11.24%

27.11% at 280℃ and 450℃ for 150min respectively.And relaxation enhances to 33.9% after 280℃ and 450℃ alternate vacuum thermal retardation.The relaxation indicates that the majority of residual stress is preserved

and thus improves the fatigue resistance of titanium alloy.The residual stress prediction model can characterize the relaxation regularity accurately.And the model is useful to analyze the residual stress thermal relaxation of other metals.