Abstract: To study the effects of comprehensive water environmental improvement measures on the aquatic ecological environment of Lihu Lake, changes and trends of the aquatic ecological environment before and after the measures were analyzed. Results showed that the water quality of Lihu Lake was remarkably improved, with the annual values of ρ(TN), ρ(TP), ρ(COD_Mn) and ρ(Chla) decreased significantly (P<0.01). ρ(TN), ρ(TP) and ρ(Chla) dropped from 5.77,0.19 mg/L and 59.90 μg/L, mean values in 1992-2002, to 3.13,0.13 mg/L and 27.12 μg/L,respectively, and ρ(COD_Mn) dropped from 7.09 mg/L to below 5.00 mg/L. The values of w(OM), w(TN) and w(TP) in the surface sediments decreased from 40.40 g/kg, 1.19 and 2.61 mg/kg in 2001 to 19.60 g/kg, 1.16 and 0.59 mg/kg in 2012, respectively. An entire ecosystem with aquatic macrophytes was set up in the ecosystem restoration areas in 2012. The effect of the projects on improving water quality was obvious after the improvements. However, some water sensory indicators, such as suspended particulate matter and transparency, did not change much, and tolerant species were still the dominant species of benthic animals. A full recovery for the ecosystem of Lihu Lake is still needed. Therefore, ecological optimization regulation focusing on increasing transparency and recovering submerged macrophytes must be further developed to accelerate the change in the stable state of Lihu Lake from algae-dominated turbid water to macrophytes-dominated clear water.