Abstract: From May 2001 to October 2002,the benthos were surveyed in 4 tidal zones at the intertidal zone of Jiuduansha (Shangsha,Zhongsha and Xiasha),the Yangtze River Estuary,by "Biological Survey Methods of Coastal Zone" of "Concise Regulation of National Coastal Zone and Coastal Resources Comprehensive Survey"(1986).According to their food preferences,the zoobenthos were classified into 5 ecological functional groups:planktophagous group (Pl),phytophagous group (Ph),camivorous group ?,omnivorous group (O) and detritivorous group (D).And they were measured and analyzed by classic diversity characteristic indxes.Among the total 38 species,we found crustacea with 20 species,mollusca with 12 species,polychaeta 4 species and other benthos 2 species.The numbers of each functional groups constituted the percentages of total benthos in proper order is Ph>Pl>O>D>C,and numbers of species constituted the percentages of total in proper order is Ph>O>Pl>C>D.The species diversity and species richness of each benthic functional groups were Zhongsha>Shangsha>Xiasha,Middle tidal zone>High tidal zone A (Phragmites australis) and Low tidal zone>High tidal zone B (Spartina alterniflora).The species composition of benthic functional groups had insignificant differences in Shangsha,Zhongsha and Xiasha,but they had distinct differences in each tidal zone.It verified that the structure of benthic functional groups is synthetical reflection of habitat gradient in the intertidal zone and fluctuation of natural environmental factors (Engle & Summers,1999).