Abstract: Using the recent seismic data and multi-beam bathymetric map, a large-scale landslide is discov-ered in Baiyun depression in the north margin of South China Sea, which is called "Baiyun landslide". Baiyun landslide is composed of three obvious parts, namely landslide root, landslide body and landslide front. This landslide shows five seismic facies:wedge weak-amplitude disorder facies, massive weak-am-plitude parallel/wavy facies, drape low amplitude parallel/wavy facies, filling medium-amplitude facies and mound/lens foreset facies. According to geography and lithology characters of seafloor sediments, the dis-tribution of Baiyun landslide which is about 13 000 km² is delineated. Because of the location in the area of deep-water hydrocarbon and gas hydrate, Baiyun landslide is significant to the exploration and development of oil, gas and hydrate.