From the benthos samples obtained during three cruises under the "China-US Joint Study Program of Marine Sedimentation Process”in the Changjiang Estuary and adjacent waters in 1980-1981, it is noted that polychaetes are very abundant in species and average about 65% of the total benthic population. The distribution of biomass and density is extremely uneven. The number of individuals in the upper 10 cm layer of sediment is very abundant and average about 66% of the total number of polychaetes in the sediment column, but it decreases with the increase in depth of the sediment. This paper mainly presents the results of analysis of the materials collected during the first cruise, emphasis being given to the presentation of data on species ?composition, distribution of biomass and density, vertical distribution and the relationship?between the distribution of' polychaetes and the sedimentary environment.