Abstract:In order to understand the purification effect of different submerged macrophyte planting density, submerged macrophyte combinations, submerged macrophytes and Carassius auratus combinations on the eutrophication water of Caohai of Dianchi Lake, four kinds of native submerged macrophytes(Stuckenia pectinata, Hydrilla verticillata, Myriophyllum spicatum, Potamogeton wrightii)and Carassius auratus were selected to carry out different combination simulation tests in test platform of Dongfeng Dam in Caohai of Dianchi Lake from September to December in 2017. The results show that the removal efficiency of TP by Stuckenia pectinata and Hydrilla verticillata with planting density of(0.63±0.06)g/L is better than that of(0.33±0.05)g/L. Different combinations of submerged macrophytes can improve the ratio of nitrogen to phosphorus in the water, and have obvious removal effect on TN, TP and Chl-a in eutrophic water of Caohai. The average removal rates of TN, TP and Chl-a in experimental groups increase by 49.67%, 9.06% and 39.41%, respectively. Carassius auratus has a significant role in promoting the growth of Hydrilla verticillata and Stuckenia pectinata. The removal rate of TN in the combination of Myriophyllum spicatum and Potamogeton wrightii increased by 87. 48%, and the removal effect of TN and TP in water was stable after the experiment. Among the submerged macrophyte combinations, the growth of Myriophyllum spicatum and Hydrilla verticillata was the best in the high nutrient water, and the concentration of TN, TP and Chl-a in the water could be effectively controlled. The combination of Carassius auratus+Myriophyllum spicatum+Potamogeton wrightii has high degradation capacity for SS, TN, TP and Chl-a in eutrophic water, which is a good combination of water purification in the ecological restoration of eutrophic water in Caohai.