As　deformation　and　defects　are　inevitable　during　the　manufacture　and　service　of　graphene　resonators,　comprehensive　molecular　dynamic　(MD)　simulations　are　performed　to　investigate　the　vibrational　properties　of　the　defective　single-layer　graphene　sheets　(SLGSs)　during　tension.　Perfect　SLGSs,　SLGSs　with　single　vacancy,　SLGSs　with　low-concentration　vacancies,　and　SLGSs　with　high-concentration　vacancies　are　considered,　respectively.　The　frequencies　of　the　perfect　and　defective　SLGSs　at　different　stretching　stages　are　investigated　in　detail.　The　effects　of　different　external　forces　are　also　taken　into　account　to　study　the　vibration　properties　of　the　defective　SLGSs.　Results　show　that　the　perfect　and　defective　SLGSs　both　successively　perform　four　stages,　i.e.,　the　elastic　stage,　the　yield　stage,　the　hardening　stage,　and　the　fracture　stage　during　stretching,　and　the　elastic　properties　of　the　SLGSs　are　insensitive　to　the　vacancy　defects,　while　the　ultimate　strain　is　noticeably　reduced　by　the　vacancies.　The　single　vacancy　has　no　effect　on　the　vibration　properties　of　SLGS,　while　the　frequency　decreases　with　the　increasing　vacancy　concentration　for　SLGS　at　the　elastic　stage.　The　frequency　of　yielded　SLGS　with　a　certain　vacancy　concentration　is　almost　constant　even　with　a　varying　external　force.