Dated from the August, 1963 to December, 1964, seventeen monthly continuous ecological investigations were made by the Institute of Oceanology, Academia Sinica in the intertidal zone of Cangkou, Jiaozhou Bay (Huanghai Sea) , with an aim to understand in detail the species composition, vertical distribution, biomass and its seasonal variation, and to discuss the biological character of several important economical species in the soft substratum beach.