In　order　to　research　into　the　microscopic　behavior　of　interface　particles　in　nano　diamond　composite　films,　the　adsorption　and　diffusion　behavior　of　carbon　and　silicon　particles　on　diamond　(001)　surface　has　been　calculated　through　the　first　principle　method.　The　configuration　energy　and　adsorption　energy　of　carbon　and　silicon　particles　at　four　high　symmetric　locations　on　the　diamond　(001)　surface　were　calculated,　and　the　diffusion　activation　energy　was　also　obtained.　It　turned　out　that　the　stable　configuration　is　along　with　the　diamond　(001)　growth　orientation.　In　addition,　the　diffusion　activation　energy　of　carbon　particle　and　silicon　particle　are　respectively　2.824　eV　and　0.475　eV.　The　difference　between　two　activation　energies　illustrated　that　silicon　particle　can　significantly　promote　carbon　particle＇s　diffusion,　in　which　the　denser　nano　diamond　composite　film　can　be　formed.