Abstract: In this work, the bentonite was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction(XRD), scanning electron microscope (SEM). The sorption of radionuclide ⁶³Ni(Ⅱ) on bentonite was investigated by batch technique under ambient conditions. The effect of contact time, pH and coexistent electrolyte cations on ⁶³Ni(Ⅱ) sorption to bentonite was examined. The results demonstrate that the kinetic adsorption data is well described by the pseudo-second-order model and the sorption of ⁶³Ni(Ⅱ) is strongly dependent on pH and ionic strength at low pH values. The sorption of ⁶³Ni(Ⅱ) is dominated by outer-sphere surface complexation or ion exchange at low pH, whereas inner-sphere surface complexation is the main sorption mechanism at high pH. In addition, the removal of ⁶³Ni(Ⅱ) to bentonite is also strongly affected by FA and cations.