Through diffusive model methods and laboratory incubation experiments, exchanging fluxes of dissolved total phosphorus(DTP) and dissolved phosphate(DIP) at the sediment-water interface of the Lake Poyang were measured, and their influencing factors were identified. The results show that the exchanging direction of DTP and DIP were unascertainable by applying the two methods, and the sediment is a source of phosphorus in most locations. The average diffusive fluxes of DTP and DIP at the sediment-water interface using diffusive model methods were 0.052 and 0.047 mg/(m²·d), respectively. The exchanging fluxes through the laboratory incubation experiments were higher than that using the diffusive model methods for all sites, and the average exchanging fluxes of DTP and DIP at the sediment-water interface were 0.25 and 0.24 mg/(m²·d), respectively. In addition, the fluxes of DTP and DIP had superior differences under different contents of dissolved oxygen and different temperatures. The exchange of DTP and DIP increased with the increasing temperature and decreasing dissolved oxygen. The results are useful for the eutrophication control and ecological restoration in the Lake Poyang.