Abstract: To investigate the effect of the LSP technique on improving the fatigue life of large structural components, this study proposes a method to perform LSP treatment on the fatigue crack propagation area of a high-strength steel-concrete composite beam. Based on existing static and fatigue test data of steel concrete composite beams, the residual stress field generated by laser shock in the crack propagation area at the lower flange of the composite beam was simulated using software ABAQUS. And the stress state data of the beam was imported into the fatigue analysis software FE-SAFE to evaluate the fatigue performance of composite beams. By comparing and analyzing the characteristics of residual stress fields under 6 laser parameters in the plate model and the fatigue life of 24 tested beams which has laser shocked, the main conclusions are summarized as follows: Under the overlap rate of 50%, laser shock can effectively generate uniformly distributed residual compressive stress on the surface of Q550 high-strength steel; There is a residual stress enhancement effect between laser points, while the depth and level of residual compressive stress field generated by multi-point impact are considerably improved compared to single point impact under the same laser parameters; Laser shock strengthening treatment in the fatigue crack development zone can effectively improve the fatigue life of steel concrete composite beams. With the laser parameters selected in this paper, the maximum fatigue life of the specimen can be increased by an average of 33.36%.