Using X-ray diffraction and the cross correlation method to determine the peak of diffraction plane (114), the residual stress distribution along the surface layer in the titanium alloy TC18 caused by shot peening was measured during step-by-step electrolytic dissolution. Relaxation of the compressive residual stress caused by shot peening at high temperatures and during cyclic stress was investigated. The characteristics of residual compressive stress field have also been analyzed; it was determined that the maximum compressive residual stress is a intrinsic parameter that is not affected by shot peening. From the above experimental results some practical laws have been derived, which offers a basis for the shot peening processing decision as it applies to the TC18 titanium alloy.