Based on the measured concentration of total nitrogen (TN) and total phosphorus (TP) in Lake Poyang in July 2011,we analyzed the spatial distribution characteristic of TN,TP,and factors affecting them.The nutrient structure and the correlations among nitrogen,phosphorus and chlorophyll-a were discussed.The results show that: The concentration levels of nitrogen and phosphorus have already reached the threshold of eutrophication.TN content has a downward trend from the east part to the west part,and from the south part to the north part,in Lake Poyang.TP contents in several dredging areas were the highest,especially in the border area between south lake and east lake.Phosphorus was limited in Lake Poyang.Comparatively speaking,nitrogen pollution was more serious,and the nitrogen and phosphorus were not the restricting factors of eutrophication.TN content was influenced by suspended sediment concentrations (SSC) as well as the water flow.It was mostly affected by the water flow in the upstream channels which were largely influenced by the land-sourced pollutants.TP content was less affected by the water flow,but it was mainly influenced by the high SSCs and the dredging activities.