Molecular dynamics simulations are performed to study the growth of diamond-like carbon (DLC) films on the atomic scale. The behaviors of incident atoms on the surface are classified into four categories: surface freezing, migration, implantation and rebounding, according to the atomic movement. The behaviors of incident atoms have an important impact on microstructure and growth mode of DLC film. The transverse migration of the atoms is the main route of film relaxation. The competition between atomic implantation and migration determines the growth mode and final structures of the film. Energy dependence of surface behaviors of deposited atoms and film structures is analyzed statistically, which deepens the understanding of DLC film growth mechanism.