Mineral_bound humic substances can modify the surfaces of minerals. The intensity of humic acid sorption on kaolinite, gibbsite and quartz is related to the nature and number of adsorption site of the minerals, the electricity and the specific surface. Calculated by the specific surface, the capability of minerals for humic acid sorption follows the sequence gibbsite>kaolinite>quartz; calculated by per unit mass of minerals, the sequence is kaolinite >gibbsite >quartz. It is thus considered that the mechanism of humic acid sorption on the minerals is affected significantly by pH value of the solution. Under the condition that pH values of the solution range from 4 to 7, the model for humic acid sorption on minerals can be described as follows: the hydrogen bonding is the main sorption form of quartz; the ligand exchange surface complexing is the main sorption form of gibbsite; and kaolinite is characterized by the existence of multiple sorption forms such as the hydrogen bonding, the ligand exchange surface complexing, the hydrophobic interaction and the cation bridging.