The uptake of Cs(I) on Beishan soil (BS) was strongly dependent on ionic strength and hardly dependent on pH over the observed pH range (6–13). The foreign cations competed with Cs(I) in the following order: K + >Mg 2+ >Ca 2+ ≈Na + >Li + . The uptake of Cs(I) was a pseudo-second-order process and the activation energy, E a , was about 2.16kJ/mol. EDS analysis suggested that the most of Cs(I) was converged on the basal plane, and a small fraction bound on the frayed sorption site. All the results suggested that ion exchange was the main approach for Cs(I) uptake on BS.