<p>Interfacial reactions at Al/Ti interface are very important for bonding and welding technologies. To understand the mechanism for controlling of interfacial reactions at Al/Ti interface, a molecular dynamics method and embedded atom potential were used to study how temperature variations and surface roughness affect the diffusion behaviors at Al-Ti interface. Sine functions are used to generate rough surface at interfaces. Results indicated that the diffusion from Ti to Al takes the key role in the interfacial reaction at Al/Ti interface. The diffusion activation energy of Ti is obviously higher than Al and can be changed by both temperatures and surface roughness of the interface. The further analysis on the RDF curves reveals that Ti and Al atoms diffuse into each other under the effect of temperature. Both the diffusion coefficients of Ti and Al are increased with the increase of temperature. The diffusion layer thickness for interfacial reaction is increased at the rough interface in comparison with the ideal interface. Prefilled atoms on the rough surface can facilitate the enhanced diffusion at Al-Ti interface.</p>