This paper presents the results of study on polychaeta in the Bohai Sea. The materials for study were collected from 101 stations in June 1982-November 1983. The species composition and distributions of biomass and density are described and discussed. Of the 189 species recorded here, 115 species were collected during cruises, 74 species were recorded before. The distribution pattern of biomass was different from that of the density. Relative abundance of biomass was found in the Liaodong Bay, but relative abundance of density was found in the central area of the Bohai Sea. Low biomass and density were at the bottoms of the Liaodong Bay,Bohai Bay and Laizhou Bay. The average biomass of polychaeta was 1.99 g/㎡, about 8.7% of the total macrobenthic infauna. The average density of polychaeta was 96 ind /㎡，about 28.1% of the total macrobenthic infauna.