Molecular　dynamics　simulations　based　on　reactive　empirical　bond-order　potentials　were　conducted　to　investigate　the　bending　and　vibration　of　defect-free　and　defective　monolayer　MoS2.　The　effects　of　constrained　boundary　conditions　and　single　sulfur　point　vacancies　were　concerned.　Three　types　of　boundary　conditions　were　discussed　in　our　work,　including　the　simply　supported　boundary,　the　pinned-pinned　boundary,　and　the　clamped-clamped　boundary.　For　the　simply　supported　beam,　typical　linear　and　nonlinear　elasticity　responses　to　the　lateral　loading　were　observed,　distinct　from　the　other　beams.　The　lower　concentrations　of　VS　defect　were　found　to　have　insignificant　effects　on　the　bending　and　vibrational　responses　of　the　defective　MoS2,　despite　a　slight　frequency　drift　appeared.　However,　higher　order　resonant　frequencies　were　arisen　in　some　monolayer　MoS2　with　randomly　distributed　VS　defects.