By observing and describing the cores, there are 11 types of lithofacies in Oligocene Zhuhai Member-2 in Wenchang Sag of Pearl River Mouth Basin, including conglomeratic sandstone or fine sandstone with cross-bedding or oblique bedding, conglomeratic sandstone with normally graded bedding, sandstone and mudstone with mixed bedding, conglomeratic coarse sandstone or fine sandstone with torn-apart fragments of mudstone, etc. Four sedimentary facies, including fan delta, delta, tidal flat, and lagoon, are recognized in Zhuhai Member-2 in Wenchang Sag according to the research on the types of lithology and electric curves, the combination of heavy minerals, the composition of rocks, and the seismic facies. It is shown that the uplifts and the bulges around Wenchang Sag provided sediments, and a series of deltas and fan deltas formed. The tidal flats widely develop in the center of the sag with a flat topography, while the lagoons distribute restrictedly in the subsiding center along Zhu Ⅲ South Fault.