Abstract: The growth of {100} oriented CVD diamond film under three different chemical models (Including Harris model, F-B model and model proposed in this paper, respectively) is simulated in atomic scale by using KMC method. The results show that: (1) the growth mechanism from CH₃ is suitable for the growth of {100} oriented CVD diamond film; (2) the deposition rate under model containing double-carbon radicals is lower than that under model containing one-carbon radicals for {100} oriented diamond film;(3) the acquisition of diamond film with low surface roughness under relatively high deposition rate is feasible; (4) the simulation results for Harris' model are in well agreement with those predicted by Harris and experiment results.