Montmorillonite/polypyrrole (MMT/PPy) nanocomposites were fabricated by in situ polymerization of pyrrole monomer in the presence of MMT. The structures of the nanocomposites were analyzed by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis and transmission electron spectroscopy. Then, the capability of MMT/PPy nanocomposites on the removal of Eosin Y from aqueous solution was systematically studied. The MMT/PPy nanocomposites showed high adsorption capacity toward Eosin Y and a maximum adsorption capacity of 112.9mg/g at 35 degrees C was achieved. The adsorption kinetics demonstrated a rapid Eosin Y uptake by MMT/PPy and the experimental data were well fitted to the pseudo-second-order model. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherms, and the results presented that the equilibrium data obeyed the Langmuir model. Thermodynamic parameters of G degrees and H degrees verified the spontaneous and endothermic nature of the Eosin Y adsorption onto MMT/PPy. Furthermore, the regeneration experiments revealed that MMT/PPy nanocomposites could be reused after treated with hydrochloric acid solution, showing potential applications in purification of dyeing effluents.