Abstract: A lot of large mass transport depositions (MTDs) have been discovered in the Quaternary strata according to recent geological and geophysical investigation results. MTDs are very popular sedimentary systems in the continental slope, which include slides, slumps and debris flows. Total area of Baiyun MTDs in Quaternary strata of the northern South China Sea is over 10 000 km². Architecture of MTDs in Quaternary strata is divided into headwall extensional domain, translational-compressional domain and toe domain compressional area. On the seismic profiles, MTDs show many structures such as:normal fault, chaotic reflection, thrust fault, pressure ridge and fold. MTDs are one of the important geological hazards,do harm to deepwater equipments and induce tsunamis. At the same time, MTDs have close relationship with formation of deepwater hydrocarbon and gas hydrate. MTDs are usually good seals in deepwater because of its lower porosity and permeability, and could be reservoirs if the slumps are originally good sandstones.