Mechanism　of　charge　collection　is　an　important　factor　for　improving　the　performance　of　diamond　particle　detector.　With　semiconductor　device　simulation　software　GSRES,　numerical　simulations　of　transport　properties　of　carriers　in　diamond　are　carried　out.　The　important　material　properties,　for　instance,　energy　gap　and　ionization　energies,　which　affect　in　simulation　are　set　same　to　pure　CVD　diamond　with　no　impurity.　The　physical　processes　of　transport　of　carriers　is　numerically　researched　by　the　drift-diffusion　model,　and　the　SRH　recombination　mechanism　in　semiconductor　material　is　the　main　cause　of　the　loss　of　charge　as　simulation　results　show.　Other　parameters,　as　electric　field　intensity,　incident　depth　and　lifetime　of　carrier,　which　influences　the　charge　collection　rate　is　studied.　The　simulation　results　are　compared　to　theoretically　analysis,　and　show　well　agreement.　This　numerical　research　method　would　be　useful　in　CVD　diamond　detector　development　and　improvement.