Bentonite is an excellent environmental material. In order to study the adsorption characteristics of bentonite for Cd(II), hydrochloric acid, sodium hydroxide and sodium dodecyl sulfonate were used as modifiers to prepare modified bentonite. The effects of pH value, initial concentration and reaction time on the adsorption of Cd(II) by modified bentonite were investigated by isothermal adsorption experiments, and the adsorption kinetics mechanism of Cd(II) by modified bentonite was also discussed. XRD analysis showed that the layer spacing of modified bentonite increased and the diffraction peak intensity decreased. The removal rate of Cd(II) by HCl-B increased with the increasing of pH value of the solution, and the removal rate of NaOH-B reached the maximum at pH=6, while B and SDS-B at pH=7. The removal rate of Cd(II) by bentonite and modified bentonite decreased with the increasing of initial concentration, and the adsorption capacity of the adsorbent increased with increasing of the equilibrim concentration of Cd(II). The equilibrium adsorption capacity of the bentonite and modified bentonite for different concentrations of Cd(II) was corresponding with the Langmuir isotherm equation, and indicating that the adsorption of Cd(II) on bentonite and modified bentonite was a monolayer adsorption process. The adsorption reaction of bentonite and modified bentonite basically reached equilibrium within 240 min. The pseudo-second-order kinetic model can better describe the adsorption mechanism, and the chemisorption was main adsorption process, and the process of liquid film diffusion and intra-particle diffusion was rate-determining step for this adsorption prosess. This study can provide reference for the treatment of Cd-containing wastewater and remediation of Cd-contaminated soil by modified bentonite.