The　reaction　mechanism　of　water-gas　shift　(WGS)　on　the　Fe3O4　(001)-B　surface　was　systematically　studied　by　using　the　density　functional　theory　(DFT)　calculation　with　spin　polarization.　The　results　show　that　for　the　WGS　on　the　Fe3O4　(001)-B　surface,　three　reaction　routes　including　redox,　association　and　regeneration　ones　coexist,　though　the　redox　and　association　routes　may　be　more　important　with　much　lower　effective　energy　barriers.　The　elementary　reaction　of　H2　formation　is　influenced　by　the　concentrations　of　surface　H　and　O　defects;　higher　concentrations　of　H　species　and　O　defects　on　the　catalyst　surface　are　beneficial　to　the　formation　of　H2.　These　results　should　be　helpful　for　a　better　understanding　of　the　WGS　reaction　mechanism　on　the　iron-oxygen　catalyst.　©　2020,　Science　Press.　All　right　reserved.