<p>Hot-dip tin-lead alloy plating experiments were carried out on the surface of 45 steel. The effects of hot-dip plating temperature and time on the morphology of the coating and the interface diffusion layer were investigated. The experimental results show that increasing the temperature and time is beneficial to obtaining a good coating surface. The interface compound formed between the coating and the substrate is FeSn₂. With the increase in hot-dip plating time at 350&#xa0;°C, the thickness of the coating and the diffusion layer generally shows an increasing trend, while the hardness of the coating shows a decreasing trend. In addition, molecular dynamics simulation was used to calculate the interface bonding energy of Sn-Pb/FeSn₂/45 steel with different FeSn₂ thicknesses at 350&#xa0;°C. The simulation results indicate that with the increase in FeSn₂ thickness, the interface bonding energy of (45 steel+FeSn₂) is greater than that of (Sn-Pb+FeSn₂). The interface bonding energies of both (Sn-Pb+FeSn₂) and (45 steel+FeSn₂) first increase and then decrease.</p>