By　a　molecular　dynamics　method　and　using　different　incident　energy　and　particle　density,　we　calculated　the　Argon-atom　bombardment　on　a　graphene　sheet.　The　results　show　that,　the　damage　of　the　bombardment　on　the　graphene　sheet　depends　not　only　on　the　incident　energy　but　also　on　the　particle　density　of　Argon　atoms.　To　compare　and　analyze　the　effect　of　the　incident　energy　and　the　particle　density　in　the　Argon-atom　bombardment,　we　defined　the　impact　factor　on　graphene　sheet　of　the　incident　energy　and　the　particle　density　by　analyzing　the　structural　Lindeman-　index　and　calculating　the　broken-hole　area　of　the　sheet,　respectively.　The　results　indicate　that,　there　is　a　critical　incident　energy　and　particle　density　for　destroying　the　graphene　sheet,　and　there　is　an　exponential　accumulated-damage　for　the　impact　of　both　the　incident　energy　and　the　particle　density　in　Argon-atom　bombardment　on　a　graphene　sheet.　Our　results　supply　some　valuable　mechanics　parameters　for　fabrication　of　potential　graphene-based　electronic　devices　with　high　particle　radiation.　©2010　IEEE.