Abstract: The atomic diffusion process of the magnetic pulse semi-solid assisted brazing interface of copper/aluminum tube was studied by molecular dynamics simulation and experiment. The results show that the atoms at the aluminum side diffusion interface mainly diffused with each other in the disordered atomic layer at the interface, and the diffusion behavior of the elements was not uniform. The diffusion speed of the aluminum matrix atoms to the filler metal was much lower than that of the filler metal atoms to the aluminum matrix. At the copper side interface, the diffusion layer is very thin (about two atomic layers thickness) and the thickness changes are not obvious at the simulated impact speeds. It is found that the simulated diffusion layer thickness increases linearly with the increase of impact speed, which is consistent with the experimental results. According to the simulation and experimental results, the relationship between the simulated interface diffusion layer thickness and the test interface diffusion layer thickness is established under the same or similar impact velocity. The simulation results can well predict the test interface diffusion layer thickness, with a maximum error rate of 2.8%.