Abstract: In order to understand the community structure of the benthos in Dagang Bay， the density， biomass and biological diversity index are studied at 12 stations of the bay on January of 2013 and April of 2013. A total of 174 macrobenthic species， including 136 species in spring and 99 species in winter， are reported. It shows that Polychaeta， Echinodermata， Mollusca and Crustaceans accounts for 86.7% of all species， which constituted most of the macrobenthos. Average biomass is 13.02 g/m2， with 20.54 g/m2 in spring and 5.19 g/m2 in winter. Average abundance is 439.80 ind/m2，with 475.42 ind/m2 in spring and 402.61 ind/m2 in winter. There are 11 species in winter and 8 species in spring with dominance index higher than 2%. The only species with IRI above 1 000 is Neoxenophthalnus obscurus in both winter and spring. The Shannon-Wiener index（H′）， Margalef index（d） and evenness index （J） are quite different between seasons and they are generally much lower in winter than spring. Cluster analysis shows that the macrobenthic communities of Dagang Bay constituted 3 groups. Besides， the result of multidimensional scaling ordination analysis （MDS） is consistent with the clustering outcome．