A static adsorption experiment was carried out to investigate the influence of initial concentration, pH, and cationic strength on adsorption of two kinds of quinolone antibiotics (ciprofloxacin and norfloxacin) on montmorillonite.The results showed that the adsorption process of ciprofloxacin and norfloxacin were consistent with pseudo-second-order kinetics, and the adsorption rate constants were 0.063 and 0.024 kg·mg-1·h-1 respectively.Adsorption isotherms were well described by Freundlich equation, and the high lgKf showed strong adsorption ability.When the solution pH was less than the pKa2 of ciprofloxacin and norfloxacin, the adsorption capacity was higher.The adsorption capacity decreased sharply when the solution pH was above the pKa2.Both cationic and zwitterionic forms of ciprofloxacin and norfloxacin could be adsorbed significantly.At higher pH, the complexation of anion on the montmorillonite surface might become the main mechanism.The concentration of Ca2+ had a great influence on adsorption.The higher the concentration, the lower the adsorption capacity of ciprofloxacin and norfloxacin.