Abstract: Taking Q235 T-shaped gas metal arc welding joint as the research object, the welding seam was strengthened by shot peening, and the effect of shot peening on the fatigue property of the Q235 welded component was investigated. The surface property before and after shot peening was characterized by surface morphology observation, microhardness test and residual stress test, the fatigue tests with stress ratio R =-1 were conducted to obtain fatigue S-N curve, and the fatigue strengths of the components were predicted by using the prediction model based on the surface residual stress. The results indicate that the surface roughness and microhardness of the welding seam increase, and residual compressive stress is introduced after shot peening. The fatigue strength of the welded and shot-peened specimens at 2 ×10⁶ cycles is 137 MPa and 207 MPa, respectively and the shot peening treatment improves the fatigue strength of the welded specimen by 51%.Compared with the experimental result of fatigue strength, the fatigue strength prediction result of the welded specimen is close, while that of the shot-peened specimen is relatively conservative.