Abstract: The effect of shot peening strength on diffusion bonding of 2219 aluminum alloy was studied by wet shot peening. The results show that with the increase of shot peening strength, the surface roughness changes from 0.1 mmN to 1.917 μm increased to 3.401 μm of 0.3 mmN. Moreover, too large shot peening strength can easily lead to slight peeling damage on the surface. The residual stress field provided by shot peening can promote the diffusion bonding process at the interface. On the one hand, it can accelerate the diffusion of solute atoms and agglomerate into phases at the interface and interact with oxides.On the other hand, it promotes the formation of recrystallized grains and eliminates the original interface by using the dynamic migration process of the new grain boundary.The joint effect of the two improves the healing effect of the interface.At 0.1 mmN, the interfacial shear strength can be increased from 12.6 MPa without shot peening to 41.1 MPa.