This paper deals with, comprehensively, for the first time, the species composition, number and its distributional characteristics of polychaetes in the soft bottom in the west of the Taiwan Stnut. This paper is sorted out on the basis of the data from the polychaete samples collected with quantitative benthic grab and quantitative trawl in the biological seasons in four cruises including 220 stations from 1984 to 1985. The survey areas were located from the Minjiang Estuary in the north to the south of the Taiwan Shoal in the south (22°23. 1'-25°43.0'N, 116°30.8'-120° 30.7'E).The survey stations are shown in Fig.1.