The experiment conducted in the river of the east suburbs of Suzhourevealed that the water hyacinth had strong ability to accumulate heavy metals andpurity the waste-water. It could considerably reduce the concentration of the heavymetals in the water, reducing the Phenol from 0.005～0.023 mgL^-3 to trace, TN from5.330 to 2.330 mgL^-1, TP 0.840 to 0.183 mgL^-1, COD 54.80 to 29.36 mgL^-1; Cu 0.57to 0.32 ppb, Pb 0.14 to 0.06 ppb, Zn 65.6 to 23.6 ppb and Cd 0.14 to 0.03 ppb, ect.Meamwhile it improved water greatly, increasing the water transparency from 36.7 to90cm. Therefore, the river water after treated by water hyacinth could reach thestandard water quality suitable for fishes. According to the experimental results, thereis no distinct second accumlation of the heavy metals in the fish bodies after the fisheshave been fed on the water hyacinth. In the fish meat the contents of the heavy metalswere lower than the healthy food standard (Hg 0.3 mgKg^-1, As 1 mgKg^-1, Pb2 mgKg^-1.