This work studied the key indicators of nutritional level of Lake Poyang in recent three years (2018-2020) including temporal and spatial characteristics of Chl.a, total phosphorus (TP) and total nitrogen (TN). The results showed that the water quality of Lake Poyang was mainly Class Ⅳ, and the pollutants exceeding national standard were TP and TN. The average concentrations of Chl.a, TP and TN during 2018-2020 were 7.6 μg/L, 0.070 mg/L and 1.30 mg/L, respectively. Presently, Lake Poyang is under medium-to-rich nutrient level. All the lake area had eutrophication periods in the year, and in all months of the year, there were regions that were eutrophic. The concentrations of TP and TN in dry seasons were higher than those in wet seasons. TP concentrations were the lowest in August and TN concentrations were lowest during August-September. The season with higher Chl.a concentration was mainly from September to November, especially in September when the mean and median values of Chl.a concentrations were 16 μg/L and 12 μg/L, exceeding the mesotrophic limit value of Chl.a, indicating that the whole lake was eutrophic. The reason was that the velocity of water in the lake slowed down due to the retreat of the "Five Rivers" in September and the mainstem of the Yangtze River still in the flood season. The waters with high Chl.a were the tail waters of rivers entering the lake, shallow lake bay and dished lake waters, such as Nanhu village, Jinxizui, Nanjishan, Banghu lake, etc. The ratio of nitrogen and phosphorus in Lake Poyang was 52, and both of TN and TP were excessive for algae production. TP should be controlled as a key point, and TN control should also be paid attention too. The reference of TP of Lake Poyang is in the range of 0.029-0.054 mg/L, and TN is in the range of 0.50-0.81 mg/L. Considering requirement of water pollution prevention and social and economic development, it is suggested that TP control objective of Lake Poyang is set in 0.050-0.100 mg/L, and TN in 1.00-1.50 mg/L. In addition, for the control section of rivers entering the lake, TP control objectives should be more strict than current 0.20 mg/L, and an appropriate TN standard should be properly established.