Abstract: Five seismic facies were identified including parallel or sub-parallel seismic facies, lenticular foreset seismic facies, incised-valley seismic facies, brush-shaped seismic facies and chaotic seismic facies through the seismic facies analysis of Baiyun depression in the Pearl River Mouth basin since 10.5 Ma and each of them standed for different kinds of depositional systems. Ulteriorly the chief depositional systems and their setup relation were analysed including shelf-margin incised-valley, turbidite fans and shelf-margin delta. At last we think the main influential factors are sediment supply, sea level change and tectonic movement. Sediment supply was the most important factor to influence depositional system upgrowth, which was the substance base. Sea level change and tectonic movement provided accommodation space for depositional system upgrowth.