Abstract: The nutrient release in the sediments of Xishan Island became the restriction on water quality improvement in Taihu Lake. Little efforts has been made to study the pollution characteristics of nitrogen and phosphorus in sediments and their responding to the overlying waters in Xishan Island. Fifteen representative sections were chosen and sampled in the autumn of 2020 (CZ1-CZ6, CX1-CX3, CX1-CX6), and the concentrations of nitrogen and phosphorus in sediments were determined. The adsorption-desorption experiments were developed under different initial ammonia nitrogen (NH₄⁺-N) and phosphate (PO₄^3--P) concentrations. The responses to the overlying water were studied to determine the dredged points. The results indicat that the average concentrations of total nitrogen and total phosphorus were 8.97 and 2.90 g·kg^-1, respectively. The average concentrations of reactive nitrogen and phosphorus were 3.77 and 1.29 g·kg^-1, respectively, which showed that the sediments in Xishan Island got higher risk of potential nitrogen and phosphorus releases. According to the results of simulation experiments, the sediments in seven points were dominated by NH₄⁺-N desorption, and the sediments in nine points were dominated by PO₄^3--P desorption. In order to maintain the stability of the water environment of Taihu Lake, the exterior pollution should be merely controlled for CZ1 and CZ2. The sediment in CZ4 needs to be dredged and measures should be taken to improve the conditions of waters and sediments in other points.