This paper studies the ecological characteristics of the composition, distribution and seasonal variation of the benthic fauna and deals with the relationship between the distribution and inhabiting environments of benthic fauna, based on the data obtained from the subtidal zone in the Jiulong Jiang Estuary August, 1980 to October, 1981.In all, 440 species were identified in this area, they might be divided into three ecological groups, i.e.estuarine, neritic euryhaline and marine, and the neritic euryhalin...