In summer a?high salinity Cold Wate Body, sometimes in the form of a cold water ring，appears at the upper water layer near the Southern Yellow Sea Warm Current Water.It measures about 90 km east-west and about 166 km south-north. In this paper the observational data for the years 1976-1979 obtained by China and Korea，and the “Oceanographical Charts of the Adjacent Seas of Ty?sen” for the years 1934-1938are used. Its monthly, yearly changes and its circulation are analysed and discussed. The result of the dynamic calculation shows that the Co1d Water Body is accompanied by a closed counterclockwise density circulation. At the end of the paper a suggestion on the cause for the formation of the Cold Water Body is presented. It may 1be a cut-off phenomenon of the cold water mass near the Southern Yellow Sea Warm Current Water.