Organic phosphorus in sediments of lake Gehu in China was investigated and researched via two methods: chemical fractionation and phosphorus-31 nuclear magnetic resonance spectroscopy. Results of chemical fractionation suggested that concentration of each organic phosphorus species in different sediments may varied highly since different condition, but showed a rank trend : residual Po> HCl-Po> Fulvic-Po> Humic-Po>NaHCO3-Po. Labile and moderately labile Po , regarded as potential P , contributed to 33.6% to 64.6% relative to total Po, which can be degraded for phytoplankton. 31P-NMR results suggested that the rank order of P species presented in NaOH-EDTA extractants of sediments: orthophosphate> monoester-P> DNA-P> pyrophosphate-P, and polyphosphate and phosphonate were almost not detected.