Mollusca were investigated quantitatively and qualitatively at fourteen mangrove stands in Hong Kong in summer (June to september, 1994)and winter(December 1994 to February 1995). Among 52 species of mollusca identified, 45 were gastropods, 7 were bivalves. Using Bray-curtis Similarity Index and cluster analysis, all sampling sections were divided into four groups, which, starting from highest density, were Cerithidea djadjariensis, Tereloralia sulcata Clithon oualaniensis and Cerithidea rhizophorarum. The species composition of Mollusca were markedly difference in different sediment Pollution might be an important factor for the low diversity index of mollusca at the Sha Tau Kok mangrove stand. Salinity was a limiting factor to the horizontal and vertical distribution of Mollusca.