Abstract: The adsorption behavior of U(Ⅵ) on illite and kaolinite was studied as a function of adsorption time, initial concentration of U(Ⅵ), adsorbent mass, pH, temperature, the type of ionic species and humic acid by the static experimental method; the structure of the illite- and kaolinite were characterized by FTIR. The experimental results display that the illite have the best adsorption effect on U(Ⅵ) at the initial mass concentration of 30 mg/L, adsorbent mass of 0.04 g, 10 h and pH=5; the kaolinite have the best adsorption effect on U(Ⅵ) at the initial mass concentration of 30 mg/L, adsorbent mass of 0.01 g, 12 h and pH=5; the adsorption capacity of illite and kaolinite is enlarged with the increasing of temperature, especially illite. Mg²⁺, CO^2-₃ and HCO^-₃ in solution significantly reduce the adsorption of U(Ⅵ) by illite and kaolinite; with the increase of humic acid, the adsorption capacity of illite improves, but the adsorption capacity of kaolinite decreases.