The　utilization　of　oxygen　vacancies　(OVs)　in　sodium　ion　batteries　(SIBs)　is　expected　to　enhance　performance,　but　as　yet　it　has　rarely　been　reported.　Taking　the　MoO3-x　nanosheet　anode　as　an　example,　for　the　first　time　we　demonstrate　the　benefits　of　OVs　on　SIB　performance.　Moreover,　the　benefits　at　deep-discharge　conditions　can　be　further　promoted　by　an　ultrathin　Al2O3　coating.　A　series　of　measurements　show　that　the　OVs　increase　the　electric　conductivity　and　Na-ion　diffusion　coefficient,　and　the　promotion　from　ultrathin　coating　lies　in　the　effective　reduction　of　cycling-induced　solid-electrolyte　interphase.　The　coated　nanosheets　exhibited　high　reversible　capacity　and　great　rate　capability　with　the　capacities　of　283.9　(50mAg(-1))　and　179.3mAhg(-1)　(1Ag(-1))　after　100　cycles.　This　work　may　not　only　arouse　future　attention　on　OVs　for　sodium　energy　storage,　but　also　open　up　new　possibilities　for　designing　strategies　to　utilize　defects　in　other　energy　storage　systems.