Fossil diatom groups from 85 samples of drill holes and 13 samples of the known depositional environment are analysed. The boundary of the Zhujiang Delta is discussed from the distribution of fossil diatom. The horizonal variation of Holocene sedimentary facies can be divided into four kinds of depositional environment corresponding to the delta plain subfacies and the delta front subfacies. The vertical variation of Holocene depositional facies shows twice changes of transgression from weak to vigorous.