Sequence of Zhuhai Formation in the Zhujiangkou Basin in the north of the South China Sea can be divided into SQ32 and SQ25.5, and Zhujiang Formation can be divided into SQ23.8, SQ21, SQ17.5 and SQ16.5.So, the three frontal sequences contain TST and HST, and the others contain LST, TST and HST.Baiyun movement which was a great tectonic event at the end of Oligocene made the Baiyun sag subside quickly and shelf break shift from south to north, then the sedimentary environment in the area changed from shelf sediments of Zhuhai Formation to shelf and slope sediments of Zhujiang Formation.This event led to the changes in geomorphologic subsidence, sequence boundary and sedimentary environment. Lots of sediments transported to slope to from a controlling deep-marine fan.So, sea-level changes, tectonic subsidence and sediment supply are the three main factors.