A comparative study of the humic acid adsorption capability between kaolinite and montmorillonite might provide important evidence for the environmental behaviors of heavy metals in soils which are developed in different climate zones.In this study, batch adsorption experiments for humic acid were carried out with two species of clay minerals (kaolinite and montmorillonite) under different solution conditions of pH values, ionic strengths and initial concentrations of the humic acid.The aim of this study was to explore the causes responsible for the generality and diversity between kaolinite and montmorillonite in the adsorption of humic acid.