Abstract: Biosorption of U(Ⅵ) by inactivated Saccharomyces cerevisiae, Deinococcus radiodurans and Eschericia coli were investigated in a batch system. The influences of initial solution pH and uranium concentration on uranium biosorption were studied. Kinetics behaviors of U(Ⅵ) adsorption on three microorganisms were researched under the condition of γ-ray irradiation. The study confirm that three kinds of inactivated microorganisms can effectively remove uranium from aqueous solution. Optimum biosorption is observed at pH 5.0. The time sequence for the establishment of uranium biosorption equilibrium is Saccharomyces cerevisiae, Deinococcus radiodurans and Eschericia coli. Cell surfaces still have abundant active groups after inactivation. Hydroxyl, amino, carboxyl, carbonyl and phosphate groups are the main functional groups which can react with uranium. The uranium removal efficiencies on three kinds of inactivated microorganisms under γ-ray irradiation are significantly lower than those of unirradiation. The reason may be that the irradiation factors change the active sites on the surface of bacteria. The intensity of the interaction between U(Ⅵ) and microorganisms is bacteria>fungus.