Abstract: In this paper,the adsorption isotherms of surfactants on liquid--solid interface have been classified systematically,and a nonuniform surface two step adsorption model has been developed by the authors.By using the adsorption isotherm equations derived from this model,the correlation of experimental isotherms of L-shape,S-shape,LS-shape,and special shape with maximum and minimum are realized.The agreement between calculated results and experimental data is good.