The effect of some common organic ligands on phosphate adsorption by hydrous Fe and Al ozides, Kaolinite and acid earth (red earth or ultiosl) was studied. In neutral solution with low concentrations of citrate, tratrate, oxalate and humate, the organic ligands appeared to be very effective in reducing phosphate adsorption on goethite, amorphous Al-oxide, kaolinite and acid soil, especially at low saturation of phosphate adsorption, Evaluation by K value from the fang. muir adsorption equation demonstrated that phosphate sorbed at the presence of organic ligands was much loosely bonded, and therefore was more available to plants as shown by the higher values of isotopic exchangeability and desorbability of the sorbed phosphate. Increasing concentrations of citrate from 10-5mol to 10-1mol decreased phosphate adsorplion on goethite, amorphous AI-oxide, kaolinite and acid soil by 37.9, 43.4, 47.7 and 80.4%, and increasing that of cartrate from 10-5 mol to 10-1mol decreased the their phosphate adsorption 27.6, 42.4, 42.7 and 50.6%, respectively. No significant amounts of Fe or/and A1 were dissolved in the equilibrium solution in the experiments.The maximum dissolution of amorphous Al- oxide in 10-1mol citrate solution was less than 0.2%. Since the newly exposed surface are very low in their affinity for phosphate and the dissolution amount of the soilds dissolved is so small that can not indicate the reduce of the total surface areas of the sorbents, the contribution of complex reaction of the organic ligands with Fe and A1 ions is very limited in the reduction of phosphate adsorption. It seems reasonable to conclude that the competition of organic ligands with phosphate for those sorption sites with high binding-energy is responsible for the reducing adsorption and increasing lability of the sorbed phosphate.