Abstract: The contents of 10 major chemical compositions of 33 samples in the surface sediments of Haitan Island seas are determined,the horizontal distributions of these composition are described and their control factors are discussed.Correlation analysis shows that positive correlation between pairs of elements,i.e.C_org,N,P,Fe,Al,Ti and Mg,is significant,and with clay they all correlate closely and are derived from terrigenous input.As to calcium and carbonate there is a high positive correlation between themselves,but there are negative correlations between them and clay as well as above elements,respectively.And they are enriched in biogenic shells in coarse sediments.Concerning Mn,it exists mainly as detritus and is also considered as authigenic deposit in gravel sand.By the aid of hierarchical clustering method of Q model,as it stands,the sediments may be classified into three geochemical sedimentary zones,which do reflect their geochemical characteristics comprehensively.