Abstract: The adsorption behavior of U(Ⅵ) on modified vermiculite by HDTMA•Br was studied with static experiments. The effects of the amount of adsorbent, pH, initial mass concentration of uranium and time on the removal rate of uranium were investigated. The unit mass of adsorption process was analyzed in thermodynamics and kinetics, and the adsorption mechanism was analyzed with FT-IR and SEM. The results indicate that the removal rate of uranium can increase with the increase of adsorbent amount and time, and the decrease of initial mass concentration of uranium. The adsorption equilibrium tends to be achieved in 120 min, and solution using flocculant and modified vermiculite can be improved. The adsorption of uranium by organically modified vermiculite is a complex process, so Langmuir monolayer adsorption theory and Freundlich adsorption theory cannot fully explain the adsorption process. The removal mechanism of uranium by using modified vermiculite fits Langmuir adsorption law, and is in line with quasi-second order kinetic equation. It is confirmed by FT-IR that —OH and SiCDS1O play an important role in the adsorption of uranium. SEM shows that the adsorption of uranium using modified vermiculite causes the structure change.