The　Au/Fe2O3　catalyst　prepared　by　the　microemulsion　method　in　Triton　X-100　was　characterized　by　XRD.　BET,　H-2-TPR,　TEM　and　XPS　techniques,　and　the　catalytic　activity　and　active　species　of　the　catalyst　for　v,,ater-gas　shift　reaction　were　discussed.　It　was　found　that　Fe3O4　was　the　active　species　for　Fe2O3　support,　and　the　simple　substance　gold　and　gold　oxide　were　the　active　species　at　low　temperature,　and　Au-FeOx.　solid　solution　was　the　active　species　at　high　temperature.　The　size　of　the　gold　particles　in　the　Au/Fe2O3　catalyst　was　less　than　10　nm　and　the　gold　particles　were　highly　dispersed　on　the　support.　In　Triton　X-100　system,　the　catalytic　activity　of　Au/Fe2O3　calcined　at　temperatures　below　150　degreesC　was　rather　low,　resulting　from　the　support　disordered.　When　Au/Fe2O3　was　calcined　at　temperatures　above　400　degreesC,　the　decrease　of　its　surface　area　and　the　amounts　of　gold　oxide　and　solid　solution　defection,　and　the　increase　of　gold　particle　size　led　to　a　decrease　in　its　catalytic　activity.　The　larger　number　of　active　sites　and　the　smaller　gold　particle　size　resulted　in　high　catalytic　activity　of　3%　Au/Fe2O3　for　the　low-temperature　water-gas　shift　reaction.