Abstract: The community structure of macrobenthic faunas was investigated in 16 stations of Qingduizi bay from 2011 to 2012, and 12 sedimentary environmental factors, 10 water environmental factors and the benthic animal community structure were analyzed by principal component separately.The results showed that 80 species of macrobenthic animals were found in four seasons, with the maximal number of species in autumn, the minimum in spring and winter, and the maximal change in species number in Annelida and arthropods.There were 5 dominant species in autumn, 6 ones in spring, 2 ones in summer, 1 one in winter, most belonging to the members in Annelida.The maximal diversity index, evenness index and richness index were observed in autumn and the minimal values in summer, higher in the farther from coastal waters, and lower closer to the coastal waters.The principal component analysis revealed that the community structure of the macrobenthos was heavily affected by sedimentary environmental factors in autumn and winter, and by water environmental factors in spring and summer.