The species composition, distribution of biomass and habitat density, and community structure of Mollusca are analysed for appraising the nuclear power station's effect on Mollusca in the mangrove of Puyuzhou, Daya Bay. The 35 mangrove area Mollusca species collected in this study were mostly euryhalinous-eurythermic and eurytopic species. Cerithidea cingulata, C. microptera, Batillaria zonalis, Geloina coaxans and Moerella culter were dominant in numbers. The average biomass and density of Mollusca were 51.15g/㎡ and 58 ind/㎡. The vertical distribution of density in different zones was in the order：middle tide zone>low tide zone >high tide zone; while that of biomass was in the order: middle tide zone>high tide zone>low tide zone. The community structure were characterised by three distribution zones: Glaucomya chinensis-laternula anatina-Cerithidea microptera at high tide zone; C cingulata-C.microptera-Geloina coaxans at middle tide zone and Moerella culter-clausinella isabellina-Angulus sp. at low tide zone. It is shown that Mollusca community structure in the mangrove area is stability. Finally the relation of Mollusca to enviromental factors are discussed briefly.