Abstract: In order to investigate the eutrophication of Poyang Lake and its variety characteristics under the change of water level, the eutrophication level of water body in the Poyang Lake region was appraised by TLI based on the periodical survey data from 15 long-term monitoring sites in Poyang Lake region during 2009-2016. At the same time, principal component analysis (PCA) was adopted to discuss the spatial-temporal characteristics of eutrophication in the Poyang Lake region as well as the relationship between the eutrophication state and water level. The results show that:(1) From the point of view of the change in one year, Poyang Lake was at the light eutrophic level in winter (January) while was at the mesotrophic level in the other three seasons, among which the summer (July) eutrophication degree was the lowest, due to the high water level in summer. The water changing period is fast. The decrease in water level in winter lead to the increase in nutrient concentration and the re-suspension of sediment and release of nutrients. In terms of annual changes, Poyang Lake in 2011, 2012 and 2014 was at the light eutrophic level, while at the mesotrophic level for the rest years. (2) In space, the Poyang Lake regions are integrally at the level of mesotrophic with little difference. Eutrophication was the highest in the eastern part of the middle lake district. (3) The change of water level in Poyang Lake had the most significant effect on eutrophication in seasonal changes during the year. The spatial distribution of eutrophication has little relation with the water level. The research shows that Poyang Lake is not at the eutrophic level on the whole, but it has the trend to become eutrophic. It is suggested that the degree of eutrophication should be reduced by controlling the pollution sources.