Clay minerology of sediments are useful in determining distribution,sources and dispersal routes of fine-grained sediments.In the present paper,clay minerals of surface sediments throughout the eastern part of Beibu Gulf has been investigated to reveal sources and transport of detrital finegrained sediments.Four distinct clay mineral suites were observed from cluster analysis of clay mineral compositions of the samples.From the distribution pattern of clay minerals,we conclude that kaolinte in the eastern gulf is mainly derived from South China Landmass;Smectite could not be transported mainly by surface current from north-western Hainan Island,and maybe minor portion of it from Red River;Illite is mainly transported by the currents from South China Sea.Chlorite has two sources,namely South China Sea and South China Landmass.The Zhujiang River derived sediments could not be one of the sources for the clay mineral here,because of very different composition and ratios.The distribution pattern of clay minerals in the eastern Beibu Gulf is mainly controlled by fine-grained sediment source and local currents.The Silt/Clay,Smectite/Kaolinte,and Smetite/(Chlorite+Illite) ratios could be used as indicators of fine-grained sediment dispersal in the gulf. Clay minerology of sediments are useful in determining distribution, sources and dispersal routes of fine-grained sediments. In the present paper, clay minerals of surface sediments throughout the eastern part of Beibu Gulf has been investigated to reveal sources and transport of detrital finegrained sediments. Four distinct clay mineral suites were observed from cluster analysis of clay mineral compositions of the samples. From the distribution pattern of clay minerals, we conclude that kaolinte in the eastern gulf is mainly derived from South China Landmass; Smectite could not be transported mainly by surface current from north-western Hainan Island, and some minor portion of it from Red River; Illite is mainly transported by the currents from South China Sea. Chlorite has two sources, namely South China Sea and South China Landmass. Zhujiang River derived sediments could not be one of the sources for the clay mineral here, because of very different composition and ratios. distribution ttern of clay minerals in the eastern Beibu Gulf is mainly controlled by fine-grained sediment source and local currents. The Silt / Clay, Smectite / Kaolinte, and Smetite / (Chlorite + Illite) ratios could be used as indicators of fine- grained sediment dispersal in the gulf.