Electrocatalysts　for　highly　efficient　oxygen　reduction　reaction　(ORR)　are　crucial　for　energy　conversion　and　storage　devices.　Single-atom　catalysts　with　maximized　metal　utilization　and　altered　electronic　structure　are　the　most　promising　alternatives　to　replace　current　benchmark　precious　metals.　However,　the　atomic　level　understanding　of　the　functional　role　for　each　species　at　the　anchoring　sites　is　still　unclear　and　poorly　elucidated.　Herein,　we　report　Fe　single　atom　catalysts　with　the　sulfur　and　oxygen　functional　groups　near　the　atomically　dispersed　metal　centers　(Fe1/NSOC)　for　highly　efficient　ORR.　The　Fe1/NSOC　delivers　a　half-wave　potential　of　0.92　V　vs.　RHE,　which　is　much　better　than　those　of　commercial　Pt/C　(0.88　V),　Fe　single　atoms　on　N-doped　carbon　(Fe1/NC,　0.89　V)　and　most　reported　nonprecious　metal　catalysts.　The　spectroscopic　measurements　reveal　that　the　presence　of　sulfur　group　induces　the　formation　of　epoxy　groups　near　the　FeN4S2　centers,　which　not　only　modulate　the　electronic　structure　of　Fe　single　atoms　but　also　participate　the　catalytic　process　to　improve　the　kinetics.　The　density　functional　theory　calculations　demonstrate　the　existence　of　sulfur　and　epoxy　group　engineer　the　charges　of　Fe　reactive　center　and　facilitate　the　reductive　release　of　OH*　(rate-limiting　step),　thus　boosting　the　overall　oxygen　reduction　efficiency.