Abstract: The adsorption behavior of Am（Ⅲ） on granite （sampled from drilling well BS01 at Beishan （BS） area—a potential candidate site for China’s high-level radioactive waste repository, the granite sample’s depth about 300 m） was studied in BS03 well groundwater by a batch technique at （25±1） ℃. The influences of pH, sulphate ion, total carbonate ion, humic acid, and concentration of the Am（Ⅲ） on the adsorption behavior were also studied, and the possible adsorption mechanism was discussed. Experimental results show that the adsorption distribution rate of Am（Ⅲ） on granite increases with increasing pH of aqueous phase. The chemical composition of the groundwater is the main factor which influences the species of Am（Ⅲ） and adsorption behavior. The adsorption mechanism of Am（Ⅲ） on granite is surface complexation. The adsorption isotherm of Am（Ⅲ） on granite can be described by Freundlich’s equation.