Nowadays, intensive breeding of poultry and livestock of large scale has made the treatment of its waste and wastewater an urgent environmental issue. which motivated this study. A wetland of 688 m2 was constructed on an egg duck farm, and water hyacinth (Eichhornia crassipes)was chosen as an aquatic plant for the wetland and used as food for duck production. The objectives of this study were to test the role of water hyacinth in purifying nutrient-rich wastewater and its effects on the ducks' feed intake, egg laying performance and egg quality. This paper shows that the constructed wetland removed as much as 64. 44%of chemical oxygen demand (COD), 21. 78%of total nitrogen(TN)and 23. 02%of total phosphorus(TP). Both dissolved oxygen(DO)and the transparency of the wastewater were remarkably improved, with its transparency 2. 5 times higher than that of the untreated wastewater. After the ducks were fed with water hyacinth, the average daily feed intake and the egg-laying ratio in the test group were 5. 86%and 9. 79%higher, respectively, than in the control group; the differences were both significant at the0. 01 probability level. The egg weight in the test group Was 2. 36%higher than in the control group(P