<p>Compound peening treatment is a typical surface strengthening process that has garnered increasing attention in engineering practice due to its combined characteristics of laser shock peening (LSP) and mechanical shot peening (SP). This study establishes a finite element grid model for compound peening treatment to investigate how variations in process parameters affect the mechanical properties of the target material in the depth direction. By comparing the characteristics of three strengthening methods, it reveals the distribution patterns of residual stress within the target material under compound peening treatment. The results indicate that during the model development, it is crucial to comprehensively consider the influence of mesh density on both LSP and SP analysis results. In compound peening treatment, as the peak pressure increases from 3.0 to 4.5 GPa, the residual stress layer depth increases from 0.19 to 0.38&#xa0;mm, while an increase in projectile velocity only enhances the subsurface residual compressive stress. Compared to LSP and SP, compound peening treatment achieves higher maximum residual stresses and deeper stress layers, with the residual stress layer depth reaching 2–3 times that of mechanical shot peening, and the maximum residual stress reaching 1.5 times that of laser peening. Furthermore, the distribution of residual stress and equivalent plastic strain (PEEQ) in the depth direction exhibits distinct segmented characteristics.</p> Graphical Abstract <p></p>