Abstract: Sorption of Th(Ⅳ) on GMZ bentonite as a function of pH, ionic strength and Th(Ⅳ) concentrations was studied under ambient condition using batch technique. The results indicate that the sorption of Th(Ⅳ) on GMZ bentonite is strongly affected by pH values (1.5-7.5) and ionic strength. The presence of humic acid increases the sorption of Th(Ⅳ) on GMZ bentonite at low pH, whereas no obvious effect is found at high pH. The sorption of Th(Ⅳ) is dominated by surface complexation and ion exchange. The sorption isotherm of Th(Ⅳ) on GMZ bentonite can be described well by Langmuir model.