Herein　the　mechanical　properties　of　graphene,　including　Young＇s　modulus,　fracture　stress　and　fracture　strain　have　been　investigated　by　molecular　dynamics　simulations.　The　simulation　results　show　that　the　mechanical　properties　of　graphene　are　sensitive　to　the　temperature　changes　but　insensitive　to　the　layer　numbers　in　the　multilayer　graphene.　Increasing　temperature　exerts　adverse　and　significant　effects　on　the　mechanical　properties　of　graphene.　However,　the　adverse　effect　produced　by　the　increasing　layer　number　is　marginal.　On　the　other　hand,　isotope　substitutions　in　graphene　play　a　negligible　role　in　modifying　the　mechanical　properties　of　graphene.　(c)　2013　Elsevier　B.V.　All　rights　reserved.