Abstract: On the base of the survey data of beam shrimp trawl in 4 seasons of 2008 and 2009 in the East China Sea, we study the seasonal characteristics of community structure of crabs in that sea area. Thirty crab species belonging to 9 families and 16 genera were caught; the average weight of catch is 3 173.05~9 835.67 g per haul. The dominant species are Charybdis bimaculata, Ovalipes punctatus (perennial), Portunus argentatus and Charybdis miles. The species richness index (D) is 0.09~1.41, the Shannon-Wiener index (H′) is 0.02~1.67, and the species evenness index (J′) is 0.02~1.00. No significant difference is found in the diversity indices among 4 seasons (P>0.05).