Abstract: The research focus on the isothermal adsorption of Cu²⁺, Pb²⁺and Zn²⁺on vermiculite in aqueous solution. Analyzing the adsorbent capacity of vermiculite for three kinds of metal cations and the influence of metal concentration for adsorbent capacity and velocity, and the type of adsorption isotherm equation were also discussed. The results showed that the adsorbent capacity of vermiculite for those cations is high; On light concentration condition, the adsorbent mechanism of those cations on vermiculite is ion exchange and adsorbent capacity followed Pb²⁺>Cu²⁺>Zn²⁺, and adsorption isotherm equation not only accord with Langmuir type, but also cohere with Freundlich type; But on high concentration condition, ion exchange and physical adsorption are concomitance and adsorbent capacity followed Zn²⁺> Pb²⁺ >Cu²⁺, and the type of adsorption isotherm equation of Cu²⁺and Pb²⁺ to meet Langmuir type and Freundlich type simultaneity, but Zn²⁺ neither Langmuir type nor Freundlich type.