Abstract: In order to get bio-iron, we put sponge iron into activatedsludge and cultivated it by SBR method.And then, we did single-factor experiment to study on influene factors and repaired effect of biological iron on simulated Cr(VI)-contaminated soil.The results show that repaired effect affected by time, pH value, dosage of biological iron and Cr(VI) initial concentration.The greater dosage of biological iron and the lower Cr(VI) initial concentration, the better repaired effect for Cr(VI), but pH value has little effect on the repaired effect. When the Cr(VI) initial concentration was 333.33 mg/kg, and 1 440 mg/kg biological iron was added to soil, after 7 days, Cr(VI) concentration decreased to 42.87 mg/kg, at this point, the removal rate was 87.14%, achieved first level standard of national soil environmental quality.So, repairing Cr(VI)-contaminated soil with bio-iron is through oxidation-reduction, electrochemistry, physical adsorption, complexation precipitation and biological action.