This study is the preliminary part in investigating the influence of surface characteristics of substrates on detergency of particulate soil. The surface of PET film was modified with NaOH and DMF for different time. Generally, the adsorption of surfactants of the film treated with NaOH and DMF was relatively higher and lower than those of non-treated film, respectively. And the adsorption of surfactant was increased with an increasing concentration of the surfactant regardless of its treated condition. But the effect of ionic strength on the adsorption of surfactant varied with the treated condition. The ${zeta}$-potential of film and the interaction energy between ${alpha}-Fe_2O_3$particle and a PET film treated with NaOH was largely higher than the original film, but those treated with DMF was lower. The adsorption of surfactants to the film and the ${zeta}$-potential of film were related more with contact angle and surface energies than with the surface roughness and surface area. A coefficient of the correlation between adsorption of surfactant to substrate and the ${zeta}$-potential of film was over 0.9.