The treatment effect of fishculture waste water by Eiodea nattalii and Hydrilla verticilla-ta undertaken in Laboratory is studied and compared.The results show as follows; (1) Eiodea nattalii and Hydrilla verticillata have strong capacity of purification on nitrogen and phosphorus, etc.in fishculture waste water.After 96 hours, treated with Eiodea nattalii, the average loss rate of toatl nitrogen, total phosphorus, amonia nitrogen, nitrate nitrogen and chemical oxygen demand is 60.7%, 53.6%, 74.4%, 59.7%, 75.1%, and 63.2%; while treated with Hydrilla verticillata, the average loss rate is 61.8%, 54.2%, 85.3%, 81.8%, 31.4% and 33.5%.(2) The purifiration capacity of the two macrophytes is restricted by water temperature, light and the content of nutrient.(3) Microbe plays an important role in the purifying proecss of fishculture waste water by the water plants.