Abstract: With the molecular dynamics simulations based on modified embedded atom method(MEAM) potentials, the discussion was presented about the diffusion behavior of the interfacial reaction in the soldering wetting process, and the theoretical analysis was used to explain the soldering diffusion process on the base metal from the view of atomic scale.The simulation results indicate that, when the reaction reaches the balance state, the mean square displacement of the atoms motion varies linearly with the reaction time step, the diffusion speed of the solder atoms in x direction is equal with that in the y direction, and both are faster than that in the y direction.Based on the equation of Einstein, the diffusion coefficients of the solder atoms spread on x, y, z directions are 2.03×10^-9, 2.05×10^-9, 5.06×10_-10cm₂/s, respectively.The diffusion coefficient of z direction is in good agreement with the experiment value, which agrees with the macroscopic proceeding in the soldering.