Abstract: The content of nitrogen and phosphorus in the different parts of water hyacinth was tested, and some other economic crops were compared with it in the paper. The results were as follows. The water content of every part tissue in water hyacinth were all higher than 90%, and the content of nitrogen and phosphorus were different in according to parts and growing stages, and the content of nitrogen and phosphorus in younger leaves were higher than that of the old. It was also found that the nitrogen and phosphorus absorption capacity of water hyacinth was higher than that of some economic crops in generally.