Colloids, the fine particles in the soil act as “carrier” preventing adsorption of pesticide to immobile soil matrix. Owing to their high specific surface area, colloids have a high sorptive capacity and can be excellent sorbent of low solubility, strongly absorbing contaminants. Studies have indicated that colloids are capable of adsorbing and enhancing the transport of a variety of contaminants in soil and ground water. The purpose of this study was determined the extent of adsorption of napropamide on bulk soils and soil colloids. Equilibrium batch adsorption experiments were performed over concentration range of 1 to 12.5 mg/L napropamide on bulk soil samples and colloidal suspensions of 100 mg/L. Freundlich coefficient Kf ranged from 3.98 to 12.82 for bulk soil and from 946 to 2 679 for soil colloids. For the colloids the Kf values decreased in the order of black soil colloid > Huangnitu colloid > calcareous soil colloid > yellow brown soil colloid > red soil colloid. A significantly positive correlation existed between Kf and organic carbon content of soil colloids (p<0.01), indicating that organic matter content of colloids was the crucial factor in affecting adsorption.