A recent study on a marine borehole WB7 in the West Lamma Channel of Hong Kong has yielded a diverse and profuse diatom flora consisting of 54 genera, 186 taxa. The diatom assemblages are dominated by coastal,intertidal and near shore shallow water species including tropical (hot-philic) and subtropical (warm-philic) planktonic varieties. According to the distribution characteristics, abundance and mean percentage of diatoms, six diatom assemblage zones can be distinguished from top to bottom . The 5th and 6th diatom assemblage zones are assigned to Holocene, and other zones (1-4 zones) are considered to be Pleistocene in age.A more systematic and intensive study shows that the continuously sampled borehole may provide important information for the reconstruction of the high-resolution Quaternary stratigraphy, palaeoclimatology and palaeoenvironment in Hong Kong.Detailed diatom studies of hole WB7 are conducive to making more accurate correlation not only between the contemporaneous strata of the study area and other parts of Hong Kong,but also between Quaternary strata in the study area and the other related sedimentary basin in adjacent sea areas.