Abstract: Abstract:In order to study the effects of aeration time on nutrient removal by an ecological plant floating bed in water, an ecological floating bed of Canna indica was taken as the study object, and an experiment was conducted consisting of four groups:the control group and aeration times of 4,8 and 12 h/d. According to the pre-experiment, the aeration rate of 2.4 m³/(m²·d) was chosen. The heights of C. indica were measured on days 0,3, 5,7, 18 and 28, with tests on ρ(DO), ρ(TN), ρ(TP), ρ(COD_Cr), ρ(NH₃-N) and ρ(NO₃^--N). After the experiment, the total amount of rhizosphere bacteria was also measured. The results showed that:1) The groups with aeration times 4 and 8 h/d had significant differences in ρ(DO) and removal rates of TN, TP, NH₃-N and NO₃^--N from the control group. 2) The plant grew best in the group with aeration time 4 h/d, with plant height of 109 cm on day 28. 3) The group with aeration time 4 h/d had the highest DO and the best nutrient removal effect; the concentration of DO reached 11.29 mg/L, while the removal rates of TN, TP, COD_Cr, NH₃-N and NO₃^--N reached 75.10%, 69.32%, 65.75%, 73.29% and 78.79% respectively on day 28. 4) The total amount of rhizosphere bacteria in the group with aeration time 4 h/d reached 1.01×10⁶ mL^-1, obviously higher than the other three groups; the control group and the groups with aeration times 8 and 12 h/d reached 4.12×10⁵,9.07×10⁵ and 7.77×10⁵ mL^-1 respectively on day 28. In conclusion, when the aeration rate was 2.4 m³/(m²·d), the aeration time of 4 h/d was helpful for cleaning the polluted water.