The distribution of ciliated protozoans was studied in Meiliang Bay of Taihu Lake from Apr. 1993 to Jan. 1994. 7 orders and 19 genus were recorded. On the basis of the trophic state index [TSI(chla)],the study area was separated into mesotrophic and eutriphic regions. Some of the genus were restricted to eutrophic situations, such as： Paramecium spp., Euplotes spp.Acti-noholina spp., Didbiium spp.Dileptus spp.,Carchesiuin spp., Opisthostyla spp. The mean monthly abundance and biomass of total ciliates were positively correlated with the trophic gradient. Ciliated protozoan was a good indicative community for the lake eutrophication. The orders (Oligotrichida and Peritrichida) dominated the ciliate assemblages and incresed with the rising of the TSI(Chla). Oligotrichida was mainly dominant in the mesotrophic region. The mean volume of the ciliated protozoans in eutrophic lake region waswith significant difference.