The Lake Nanhu (30°29'N,114°21'E) situated in Wuhan City, Hubei Province of China, is an eutrophic shallow lake along the middle reaches of the Yangtze River, with a main surface of 550 hmZ of aquaculture.Macrozoobenthos were collected at 5 sampling sites both seasonally and randomly in the Lake Nanhu during the period of investigation from August 2005 to May 2006. With the input of massive nutritional salts and the deteriorationof the water quality, the community structure and biodiversity of macrozoobenthos had changed in the Lake Nanhu.Few species like mollusk had already been seen in the lake. Predominant species were limnodrilus hoffmeisteri,Tubifex,tubifex, Branchiwa souxrbyi, Tanypus pua.}t如nnis and Propsilocerus akamus at present. Level distributionsdensity of L.hoffmeisteri were V>Ⅲ>I<>I>N and T. punctipennis were II>I>>Q>N>V .The largestdensity of L ho ffmeisteri in May was 3802 ind. /m²,so was the least in August The largest density of T. pu>2. The largest distributions depth was 25 cm, while 99% of Oligochaeta and Chironomid larvae lived in depth of 0-20 cm in the sediment. Wet weight biomess of Oligochaeta's was 176759. 35kg, Chironomid larvae was 46810. 30 kg, and freshwater snails was 899. 34 kg in Lake Nanhu. Macrozoobenthos canclear away 3463.61 kg TN and 350. 92 kg TP from the lake, but their efficiency is limited, compared with huge nutrition salt source of the lake.