A new code was developed by the method of kinetic Monte Carlo technique to investigate the three-dimensional CVD thin-film growth process. Cu atoms were randomly deposited on L×L Cu (100) lattice. The growth includes several basic processes: deposition, surface diffusion, atom detachment, atom nucleation, clusters growth and so on. Film quality is characterized by several parameters including surface entropy Sk, roughness Rk, flatness parameter σk etc. It’s found that lower temperature and less monolayer always come with coarse surface until it reaches the critical temperature Tc, which is consistent with experimental result. Surface entropy is a new concept used by analogy with information entropy in the field of communications. It’s also discovered that traditional description of film roughness Rk is not appropriate. At last, it’s explained that it is reasonable using surface entropy to describe films over all quality.