In　order　to　improve　the　quality　of　nano-diamond　films,　a　new　type　of　diamond/Si　nano-composite　films　was　proposed.　The　monolayer　Si　interface　and　monolayer　SiC　interface　were　studied　in　this　paper.　The　system　total　energies　and　adsorption　energies　of　monolayer　Si　and　monolayer　SiC　on　diamond　(001)　surface　were　calculated　with　first　principle　method　based　on　the　density　functional　theory　(DFT)　to　investigate　the　stability　of　the　two　kinds　of　interface　structures　in　the　Diamond/Si　nano-composite　films.　Moreover,　the　variation　of　the　configuration　energy　and　structures　when　the　hydrogen　atom　and　CH2　radical　adsorbed　on　the　two　kinds　of　interfaces　were　researched　to　verify　whether　the　diamond　phase　was　able　to　nucleate　and　grow　or　not　in　the　process　of　diamond/Si　nano-composite　films　deposition.　It　turned　out　that　(1)　the　diamond　surface　structure　which　is　terminated　by　monolayer　silicon　atoms　is　not　very　stable.　It　is　difficult　to　form　the　stable　monolayer　Si　interface　in　diamond/Si　nano-composite　films;　(2)　the　monolayer　SiC　interface　with　the　carbon　and　silicon　atomic　ratio　of　1:1in　which　the　carbon　and　silicon　atoms　are　located　in　the　same　row　respectively　is　a　more　stable　structure.　The　interface　is　conductive　to　the　second　nucleation　in　the　process　of　diamond　growth.　(C)　2014　Elsevier　B.V.　All　rights　reserved.