This paper presents the results of ecological study of the macrobenthic fauna in the Changjiang River Estuary. The materials for study were collected from 35 stations west of 123°E and 30°30′-32°00′N, in April and October 1988. The distribution of species of macrobenthos and their biomass and density were described and discussed. After flood season, the center of the distribution of some species drew off shore and near the northern of the explored region, but the estuarine species, for example Heterocossura aciculata, developed again in the river mouth. The number of species and the biomass and density of macrobenthos, particularly Mollusca, decreased. The areas of high biomass and density visibly receded to the southern and northern of the explored region, particularly in the south.