A　molecular　dynamics　study　on　nanoindentation　experiments　is　carried　out　for　some　single-layer　rectangular　graphene　films　with　four　edges　clamped.　Typical　load-displacement　curves　are　obtained,　and　the　effects　of　various　factors　including　indenter　radii,　loading　speeds,　and　aspect　ratios　of　the　graphene　film　on　the　simulation　results　are　discussed.　A　formula　describing　the　relationship　between　the　load　and　indentation　depth　is　obtained　according　to　the　molecular　dynamics　simulation　results.　Young＇s　modulus　and　the　strength　of　the　single-layer　graphene　film　are　measured　as　about　1.0　TPa　and　200　GPa,　respectively.　It　is　found　that　the　graphene　film　ruptured　in　the　central　point　at　a　critical　indentation　depth.　The　deformation　mechanisms　and　dislocation　activities　are　discussed　in　detail　during　the　loading-unloading-reloading　process.　It　is　observed　from　the　simulation　results　that　once　the　loading　speed　is　larger　than　the　critical　loading　speed,　the　maximum　force　exerted　on　the　graphene　film　increases　and　the　critical　indentation　depth　decreases　with　the　increase　of　the　loading　speed.