Abstract: The clay minerals composition of the surface sediments in the South Yellow Sea from 295 stations were studied with focus on clay assemblages and their distribution pattern as well as provenance. The research results show that illite dominates in surface sediments of the South Yellow Sea with smectite or kaolinite as the second and chlorite the lowest. The assemblage of illite-smectite-kaolinete-chlorite is the main type of the clay minerals assemblage in the area,followed by the illite-kaolinete-smectite-chlorite assemblage. Clay minerals are mainly from the Yellow River and Yangtze River.Materials from both the recent and the ancient Yellow River deposited mainly in the western, middle part of the South Yellow Sea, while the substance from the Yangtze River deposited mainly in the southwestern and southern parts. In the eastern part of the study area, an influence of the material from the Korean peninsula was observed.