Abstract: Phosphate adsorption on the surfaces of soils with variable charge were investigated in the presence of two or three kinds of organic acids. Results showed: (1) The amount of phosphate adsorption were remarkably influenced by both the types and total concentrations of organic acids in the solution, and also their individual concentration; (2) The effect of organic acids on phosphate adsorption was different for soils with various components and surface properties; (3) The comprehensive effect of coexisting organic acids on phosphate adsorption didnt equal to the sum of every organic acids at single system. Therefore, it seems necessary to understand the interaction among phosphate, organic acids and soil minerals.