Abstract: A survey on two rocky intertidal sections in Dongdai Village of Nanri Island was carried out from April 2011 to February 2012.73 species were identified and analyzed, including 49 species of Mollusca, 8 species of Algae, 7 species of Crustacea, 6 species of Echinodemata, 1 species of Polychaeta, and 2 others. The average biomass of benthos in the intertidal zone was 1 658.01 g/m², and the average inhabit density was 23 420 ind/m². The biodiversity index varied 0.42~1.84; the index of Margalef's species richness varied 0.67~1.71; the Pielou's evenness varied 0.12~0.42; and the index of Simpson's dominance varied 0.13~0.61. The distribution characteristics was the result of multiple factors, including habitat, seasonality, and human activity and so on.