This paper reports the quantitative dynamics of macrobenthic fauna in JiaoZhou Bay. The materials studied were collected seasonally from 10 stations in the period from February 1998 to November 1999. Among the 195 species of macrobenthic fauna collected, 79 were Polychaeta species, 39 were Mollusca species, 52 were Crustacea species, 8 were Echinodermata species, 17 were species of all other groups. The average total biomass was 151.18g/m2 and total density was 386.3 ind./m2 which were twice and 2.9 times that of 5 years ago respectively. The highest biomass occurred in autumn, being 240.32 g/m2, and the lowest biomass was in spring, being 62.97g/m2, while the highest biomass occurred in spring and the lowest biomass in winter 5 years ago. The highest density was in spring, being 515.10 ind./m2, and the lowest density was in summer, being 270.75 ind./m2, while the highest density was in summer and lowest density in autumn of 5 years ago. Mollusca and Polychaeta were the key contributors to biomass and density respectively.