Abstract: The sorption behavior of radionuclides onto geological media such as rocks, clays or minerals has been an important part in the evaluation of the physicochemical behavior of radionuclides in the environment. Herein, the attapulgite sample was characterized by X-ray diffraction and scanning electronic microscopy, and the sorption of U(Ⅵ) on the Na-attapulgite was investigated as functions of contact time, ionic strength, pH, fulvic acid (FA) and temperature by using a batch technique. The results indicate that the sorption of U(Ⅵ) on Na-attapulgite depends on pH, ionic strength, temperature and humic acid. The sorption of U(Ⅵ) on Na-attapulgite is a kinetically fast process, and the sorption equilibrium can be achieved in about 2-3h. The sorption of U(Ⅵ) on Na-attapulgite decreases with the increasing concentration of NaCl solution at pH<5.5, whereas increases at pH>8.0. The sorption of U(Ⅵ) sharply increases with increasing pH at pH<6.0, but decreases at pH>8.0. Surface complexation may be the main sorption mechanism at high pH values, and ion exchange at low pH values. The sorption of U(Ⅵ) increases with increasing temperature, indicating the sorption process of U(Ⅵ) on Naattapulgite is endothermic. Enthalpy (ΔH^〇), entropy (ΔS^〇) and Gibbs free energy (ΔG^〇) were calculated from the temperature-dependent sorption data, the results indicate that the sorption of U(Ⅵ) on Na-attapulgite is a spontaneous process. The presence of fulvic acid enhances the sorption of U(Ⅵ) on Na-attapulgite.