Abstract: Three typical core sediments located in different ecological sites were selected to study the content and vertical distribution characteristics of organic matters and organic phosphorus in Gehu Lake, characterizing the bioavailability of different organic phosphorus species of these sediments by chemical sequential fractionation and ³¹P-NMR technical. The results suggest that the content of organic matters decreased in vertical direction, and represented a distinct tendency in different ecological sites meanwhile:fishery farming area > estuary area > float grass area. The organic phosphorus species followed the order of Res-P > HCl-Po > NaOH-Po > NaHCO₃-Po, and most of potential biological phosphorus NaHCO₃-Po and NaOH-Po appeared in upper sediments. With the results of ³¹P-NMR, orthophosphate was dominant in biological phosphorus, P-monoester occupied a large proportion of organic phosphorus components, P-diester varied greatly by different ecological lake areas.