The　molybdenum　disulfide　(MoS2),　as　a　promising　and　nonprecious　catalyst,　has　attracted　growing　interest　towards　the　hydrogen　production,　especially　the　dissociation　of　water　and　the　hydrogen　evolution　reaction　(HER).　However,　the　known　active　sites　are　limited　to　edges　and　one　primitive　cell　missing　vacancies.　Herein,　the　potential　catalytic　activities　of　Mo-vacancies　in　the　inert　basal　plane　of　MoS2　are　investigated　by　means　of　first-principle　density　functional　theory　(DFT)　calculations.　Mo-vacancies　was　found　to　have　the　promising　catalytic　activities　for　the　splitting　of　H2O　and　have　the　comparable　or　even　better　catalytic　activities　for　the　HER,　in　compared　with　the　precious　Pt.　Moreover,　the　catalytic　activities　of　these　active　sites　are　well　understood　in　terms　of　the　analysis　of　the　adsorption　energy,　the　total　and　partial　density　states　(DOS,　PDOS),　and　the　Bader　charge　transfer.　Our　theoretical　works　suggest　that　formation　of　the　specified　vacancy　defects　on　the　inert　basal　plane　will　enhance　the　catalytic　activities　of　MoS2　for　the　dissociation　of　H2O　and　the　HER,　which　improves　the　efficiency　of　hydrogen　production.