The alloying processes of solid-solid (at 400K) and liquid-solid (at 500K) Li-Pb interfaces are investigated by molecular dynamics simulations with embedded-atom method (EAM) potentials.As a comparison, a critical Li-Pb interface at 450K near the melting point of Li is also studied.Three-stage feature, including the interface disordering, nucleation and growth of an intermetallic phase (B2-LiPb), has been clearly observed in these three cases.It is found that the alloying products are the same, however, the nucleation of the intermetallic phase at the solid-solid Li-Pb interface is earlier than that in the other two cases.The block Li in the solid-solid interface sample keeps the body-centered cubic structure during the course of simulation, while in the critical Li-Pb interface sample, it collapses from the excessive lattice distortion.As simulation time increasing,the interface widths increase gradually with decreasing growth rates, and the growth rate is the largest for the liquid-solid interface and the smallest for the solid-solid interface.The interface width of the solid-solid Li-Pb interface saturates at about 0.3ns for the diffusion barrier-B2-LiPb almost traversed across the entire interface plane at that time.