In order to provide theoretic base for reasonable utilization of fisheries resource and to offer ecological strategy to the assessment and protection of aquatic environment, we studied the community structure and biodiversity of Daoguanhe Reservoir, Hubei Proince bimonthly in 1999.Macrozoobenthos were sampled from thirteen sites.Seven taxa of zoobenthos were identified.They belonged to 16 genera, 9 families, 4 phyla.Those were 3 species of mollusks, 5 species of oligochaetes, 8 species of aquatic insects and 1 of nematode.The density and biomass of the benthic animals were 142 ind/m² and 0.99 g/m², respectively.The dominant species were Tokunagayusurika akamusi and Limnorilus hoffmeisteri.The seasonal density variation order was spring > winter > autumn > summer;and biomass ranked as spring > winter > summer > autumn.The horizontal variation tendency of both density and biomass were the upper reaches > the reservoir bay > the middle reaches > the lower reaches.There was a significant negative relation between benthos biomass and water depths;but no pronounced relations between biomass and water temperature, sediment TN, TP or pH.Water quality of the reservoir was evaluated using Goodnight-Whitley index and other biological and biodiversity indices.The results demonstrated that the reservoir was polluted.We suggest Shannon-Wiener index and Margalef index are not fitted to the assessment of water quality in deep reservoirs.