Abstract: This paper report s on the result s of investigations on molluscs in four kinds of habitat s. 38 species of molluscs , belonging to 23 families , are recognized. The result s show that values of species richness indices at rocky shores ( D = 4. 33 to 9. 38) are larger than those of muddy and sandy beaches ( D = 4.33 to 6.49) , and those of muddy and sandy beaches are larger than those of sandy beaches ( D = 2. 89) . The studies of species diversity also show that values of species diversity indices at rocky shores ( H′= 0. 429 to 0. 842) are larger than those of muddy and sandy beaches ( H′= 0. 315 to 0. 450) , and those of sandy beaches ( H′= 0. 182) . The results of systematic clustering based on similarity coefficients show that the distribution and quantity of molluscs is affected by sediment s , tide and pollution.