Abstract: Forms and occurrence characteristics of organic phosphorus and inorganic phosphorus in the surface sediments of Lihu Lake were studied by sequential extraction method, and the bio-availability and release risk of phosphorus in various forms were also discussed, in combination with the spatial distribution characteristics of the total dissolved phosphorus in the interstitial water. IP was the main phosphorus form in Lihu Lake sediments, and w(IP) accounted for 58.09% of w(TP). The value of w(Ca-P_i) was (207.75±48.56) mg/kg, accounting for 48.97% of w(IP), and Ca-P_i was the main form of IP. NA-P_o dominated OP in the sediments, and w(NA-P_o) was (195.33±50.73) mg/kg, accounting for 67.09% of w(OP). Phosphorus in pore water was dominated by DIP; the proportion of ρ(DIP) in ρ(DTP) was from 11.86% to 86.13%, with mean value of 59.65%. w(WA-P_i), w(PA-P_i), w(Fe/Al-P_i), w(WA-P_o) and w(PA-P_o) had significant positive correlations with ρ(DTP) in the pore water, and w(Ca-P_i) was positively associated with ρ(DTP), but there was not a significant positive correlation between w(NA-P_o) and ρ(DTP). Even the exogenous phosphorus was under effective control, the possibility for IP and OP with a high activity in sediments to keep the lake in eutrophic state still exists.