Perfect　monolayer　molybdenum　disulfide　(MoS2)　is　a　promising　catalyst　for　the　hydrogen　evolution　reaction　(HER)　and　the　dissociation　of　water　molecules,　but　its　surface　severely　limits　the　catalytic　properties　of　the　material.　The　known　active　sites　are　marginal　and　include　protocell　(MoS2)　and　single　atom　(Mo,　S)　vacancies.　In　this　article,　we　used　the　first-principles　density　functional　theory　(DFT)　calculations　to　study　the　effect　of　strain　engineering　on　the　catalytic　activity　of　VMo-SLMoS2　for　the　HER.　We　found　that　the　strain　effect　on　the　HER　catalytic　activity　of　VMo-SLMoS2　was　achieved　by　changing　the　interaction　between　the　S　and　Mo　around　the　vacancy.　A　4.5%　biaxial　compressive　strain　was　optimal,　and　the　Gibbs　free　energy　is　only　-0.03eV　and　-0.04eV　at　the　active　site.　©　2002-2012　IEEE.