Phosphorus fractions and phosphorus adsorption characteristics of Xuanwu Lake sediments were analyzed. In this study, according to the Standards, Measurements and Testing (SMT) protocol, the sediment phosphorus is fractionated into Cone. HCl-P, NaOH-P, HCl-P, organic P (OP), inorganic P (IP). The results show that the Cone. HCl-P content in the sediments ranges from 567.89 to 1196.89 mg kg-1. The biologically available phosphorus (BAP) ranges from 181.15 to 658.69 mg kg-1 in the Xuanwu Lake sediments. The content of native adsorbed phosphorus omegaNAP varies greatly from 15 to 79.6 mg.kg-1 and zero equilibrium phosphorus concentration CEPC ranges from 0.0922 to 0.367 mg ldr L-1. After the external load is reduced, the inherent phosphorus present in sediments will be a major threat to the water quality and be a predominant factor determining the trophic status of the lake.