Co3O4　is　an　important　catalyst　widely　used　for　CO　oxidation　or　electrochemical　water　oxidation　near　room　temperature　and　was　also　recently　used　as　support　for　single-atom　catalysts　(SACs).　Co3O4　with　a　spinel　structure　hosts　dual　oxidation　states　of　Co2+　and　Co3+　in　the　lattice,　leading　to　the　complexity　of　its　surface　structure　as　the　exposure　of　Co2+　and　Co3+　has　a　significant　impact　on　the　performance　of　the　catalysts.　Although　it　is　acknowledged　that　different　facets　exhibit　varied　catalytic　activities　and　different　abilities　in　hosting　single　atoms　to　provide　active　centers　in　SACs,　the　Co3O4　surface　structure　remains　under-investigated.　In　this　study,　major　facets　of　{111},　{110},　and　{100}　were　studied　down　to　subangstrom　scale　using　advanced　electron　microscopy.　We　noticed　that　each　facet　has　its　own　most　stable　surface　configuration.　The　distribution　of　Co2+　and　Co3+　on　each　facet　was　quantified,　revealing　a　facet-dependent　distribution　of　Co2+　and　Co3+.　Co3+　was　found　to　be　preferentially　exposed　on　{100}　and　{110}　as　well　as　surface　steps.　Surface　reconstruction　was　revealed,　where　a　subangstrom　scale　shift　of　Co2+　was　confirmed　on　facets　of　{111}　and　{100}　due　to　polarity　compensation　and　oxygen　deficiency　on　the　surface.　This　work　not　only　improves　our　fundamental　understanding　of　the　Co3O4　surface　structure　but　also　may　promote　the　design　of　Co3O4-based　catalysts　with　tunable　activity　and　stability.