Poyang Lake is the biggest freshwater lake in China,and its water quality is good among the five biggest freshwater lakes.But it has been observed with accelerated nutrient enrichment in the past two decades.The eutrophication evolvement processes and the main pollution sources of Poyang Lake were analyzed.The results showed that the water quality had deteriorated,and the Poyang Lake was entering into mesotrophic even eutrophic state gradually.The main pollution sources come from the urban domestic sewage,the industrial sewage and the non-point pollution.And the countermeasures for the aquatic environmental protection of the Poyang Lake were discussed.