The adsorption behavior of the organobentonite (CTMAB-bentonite) modified with dithizone for lead ion in water was investigated.A sort of cheap sorbent was prepared through modifying organobentonite with dithizone and was characterized with FT-IR.By means of flame atomic absorption spectrometry (FAAS), the adsorption situation and mechanism were studied.The results showed that after treating bentonite with cetyl trimethyl ammonium bromide (CTMAB),dithizone could be immobilized on the bentonite firmly.The lead ion in water could be adsorbed quantitatively on the organobentonite modified with dithizone, and the adsorbed quantity was affected by pH value of medium, temperature and time.The adsorption behavior followed a Langmuir adsorption isotherm and a pseudo-second-order kinetic model.The enthalpy change of the adsorption process was 58.432 kJ·mol-1,and Gibbs free energy change was negative at different temperatures.The reaction of adsorption was an spontaneous, endothermal process. The adsorption behavior of the organobentonite (CTMAB-bentonite) modified with dithizone for lead ion in water was investigated. A sort of cheap sorbent was prepared through modified organobentonite with dithizone and was characterized with FT-IR.By means of flame atomic absorption spectrometry ( FAAS), the adsorption situation and mechanism were studied. The results showed that after treating bentonite with cetyl trimethyl ammonium bromide (CTMAB), dithizone could be immobilized on the bentonite firmly. The lead ion in water could be adsorbed quantitatively on the organobentonite modified with dithizone, and the adsorbed quantity was affected by pH value of medium, temperature and time. The adsorption of the adsorbent was followed by a Langmuir adsorption isotherm and a pseudo-second-order kinetic model. The enthalpy change of the adsorption process was 58.432 kJ · mol -1 , and Gibbs free energy change was negative at different temperatures. The reaction of adsorption was an spontaneous, endothermal process.