Abstract: The tin bronze/steel diffusion bonding molecular dynamics model was established. The diffusion behavior of tin bronze/steel at different diffusion temperatures （1 073−1173 K） for 8 ns at the atomic scale was studied, and the diffusion mechanism was analyzed. The results show that under different diffusion temperatures, asymmetric diffusion phenomena appeared at the diffusion interface between tin bronze and steel by simulation, namely more iron atoms diffused into copper and the diffusion distance was longer. With the increase of diffusion temperature, the thickness of the diffusion layer and the mean square displacement of iron and copper atoms both increased. The diffusion bonding joint prepared at 1103 K for 1 h had a concave-convex interlocking morphology at the diffusion interface, and Fe-Cu solid solution was formed at the interface. The thickness of diffusion layer at 1103 K was 5.0 μm, and the tensile strength reached 260 MPa. Interdiffusion of elements occurred between tin bronze and steel. The diffusion distance of iron in tin bronze was relatively long, while copper was only present in the steel near the interface.