After widely screening, a kind of bacteria was obtamed, which is casy to culture and hasstrong ability of reducing Au3+ to Au0. It was used to prepare the highly dispersive Au/a-Fe2O3catalyst by in situ reducmg the Au3+ ions impregnated on a-Fe2O3 supporter to Au0 particles.with a mean size of 5 nm, under the condition of 28℃ and pH 4.5. The reductive degree ofAu3+ was up to 100%. This catalyst showed good catalytic property for the oxidation of carbonmonoxide, the percent conversion of 1.5% CO, balanced withe air was up to 100% under thecondition of 25~28℃and GHSV 500mL·h-1·g-1, and the percent conversion of 100% lastedfor 75 h at 25 ℃.