Abstract: The effect of different concentrations of phosphorus on phosphorus distribution among lemna minor-overlay water-sediment was studied by stimulated test in laboratory.The result showed that the absorbed efficiency of phosphorus by lemna minor rose with the increase of the phosphorus concentration in overlay water.The phosphorus concentration in overlay water had obvious impact on the activity of alkaline phosphates in the sediment.The phosphorus distribution between overlay water and sediment was mainly related to the difference of phosphorus contents of them.The lower the concentration of dissolvable phosphorus was,the more activity the alkaline phosphatase in the sediment had.In the concrete,a reducing tendency of phosphorus content in sediment was obtain when concentration of phosphorus in overlay before cultivating was no more than 0.5 mg/L and a raising tendency when the concentration fluctuated from 2 to 50 mg/L.