The kinetics and thermodynamics of Pb2+、Cd2+、Ni2+、Ag+ adsorption on a low-cost adsorbent, natural vermiculite, were studied under the condition of pH=4～5, t=(20±1) ℃. Pseudo second order model was used to describe the reaction rate,and the adsorption capacity calculated by the model was consistent measurement, with the correlation coefficient（r） more than 0.9. The kinetic rate constants for metal ions are in the order of Ag+＞Pb2+＞Cd2+＞Ni2+.The adsorption isotherms for metal ion follow both Langmiur and Freundlich isotherm model, with r is more than 0.99. The adsorption capacities for metal ions are in the order of Pb2+＞Cd2+＞Ag+＞Ni2+. Also, the competitive adsorption of four metals adsorbed on vermiculite was studied. The Pb2+ is most effectively adsorbed on vermiculite and the selectivity of metal ions adsorbed on vermiculite is in the order of Pb2+＞Cd2+＞Ni2+＞Ag+.
