Abstract: A simulation experiment was carried out to study effect of Eichhornia crassipes on removing nitrogen and phosphorus from eutrophicated water as affected by hydraulic loading (0.14,0.20,0.33,1.00 m3·m-2·d-1). The average concentrations of total nitrogen (TN), ammonia-nitrogen (NH₄⁺-N), nitrate-nitrogen (NO₃^--N) and total phosphorus in the influent were 4.85,1.33,2.92 and 0.50 mg·L^-1, respectively during the experiment. Results of the experiment show that the effect of the Eichhornia crassipes purifying system was satisfactory. When the hydraulic loading was low (0.14 and 0.20 m3·m-2·d-1), the average concentrations of TN, NH₄⁺-N and TP in the effluent all met the national standard for surface water body quality Ⅳ(GB 3838-2002). But when the hydraulic loading was raised to 1.00 m³·m^-2·d^-1, the average concentrations of TN, NH₄⁺-N, NO₃^--N and TP in the effluent increased significantly. Although the removal rates of TN and TP decreased,the load removal rates of TN and TP increased with the increasing hydraulic loading for the Eichhornia crassipes purifying system. For the four hydraulic loadings (0.14,0.20,0.33 and 1.00 m³·m^-2·d^-1), the average removal rates of TN and TP by the system were 84.95% and 80.65%,73.87% and 73.04%,51.60% and 64.05%,30.77% and 47.79%,respectively,that is,decreasing with rising of hydraulic loading,and the corresponding for TN and TP loading removal was 0.58 and 0.06,0.72 and 0.07,0.83 and 0.11,1.47 and 0.23 g·m^-2·d^-1, respectively, that is,increasing with rising of hydraulic loading. Comprehensively considering removal efficiency and wastewater treatment capacity, the hydraulic loading should be controlled at 0.33 m³·m^-2·d^-1 for the Eichhornia crassipes purifying system in conditions like this experiment.