The　electron　transfer　in　photocatalytic　reaction,　including　electron　transfer　between　the　components　in　the　catalyst,　electron　transfer　between　reactant　molecules　and　catalysts.　Fe2+/Fe3+　and　oxygen　vacancies　(VOs)　were　simultaneously　introduced　in　Fe-In2O3,　the　5　wt%　Fe-In2O3　exhibited　a　13.7-fold　increase　in　activity　(4.80　mmol　center　dot　g-　1　center　dot　h-　1)　compared　to　the　In2O3　and　a　CO　selectivity　of　approximately　84.32　%.　Multiple　in-situ　techniques　indicated　that　the　doping　of　FeOX　serves　to　effectively　modulate　the　concentration　of　VOs,　FeOX　and　In2O3　form　a　p-n　heterojunction　interfacial　structure　and　match　energy　bands,　promoting　carrier　separation.　More　importantly,　Fe2+,　In2+,　and　VOs　serve　as　electron-donating　adsorption　sites,　increasing　the　number　of　electrons　received　by　CO2　and　H2O,　which　causing　pre-reduction　activation　of　the　reactant　molecules.　Eventually　the　dualreduction　reaction　of　CO2　and　H2O　were　realized,　subsequently,　CO2　was　selectively　converted　into　CO　through　intermediate　species　such　as　formate.　This　study　employs　Fe2+　and　VOs　to　synergistic　optimize　the　progressive　transfer　of　photogenerated　electrons,　and　presents　a　novel　approach　for　elucidating　the　catalytic　mechanism.