Abstract: The species composition,biomass and microenvironmental characters of cattail population aredetermined.The roles of this population in filtering and adsorbing sand deposition,absor-bing and accumulating heavy metals and providing and maintaining better environment foraquatic higher plants,algae and fishes are discussed,the species and amount of algae andfish and their heavy metal contents are measured,and the ecological sequences of aquatic organisms in purification pond are summarized.The key for improving the purification effectsis to increase the biomass of cattail plants by means of rational close planting.

Key words: Forest ecosystem, Soil microorganism, Mycorrhizal fungi, PGPR, Microflora