Abstract: In order to explore the influence of the phosphorus concentration in the overlying water on the vertical distribution of phosphorus in the pore water of the sediments,a series of laboratory experiments were conducted. The phosphorus concentration in the pore water was measured using the technique of diffusive equilibration in thin films（ DET）,based on which the vertical changes of the phosphorus concentration in the pore water were analyzed,and the relationship between the phosphorus concentration in the overlying water and the phosphorus content in the sediment pore water,as well as the phosphorus concentration in the pore water at the overlying water-sediment interface was investigated. It shows that the greater the phosphorus concentration in the overlying water,the longer it takes for the vertical distribution of phosphorus in the sediment pore water to reach equilibrium,and the greater the concentration of phosphorus in pore water and its concentration gradient at the same vertical position. The phosphorus concentration in pore water and its concentration gradient decrease with the increase of the depth. Phosphorus diffusion in the pore water of surface sediment is the strongest; however,the phosphorus concentration in the overlying water has no significant effect on phosphorus concentration in the pore water of the substratum sediment. After the adsorption reaches equilibrium,the phosphorus concentration in the sediment pore water and in the pore water at the overlying water-sediment interface have a power function relationship with that in the overlying water,and the remaining phosphorus in the sediment pore water only accounts for 2. 26%-3. 80%,because most of the phosphorus in the overlying water is adsorbed by the sediments.