Abstract: deep-water gravity-flow depositions are generally inferred that the sediments deposited by gravity flows outsidea continental shelf, the genesis, process and facies of such deposits show significant differences from traction current sediments such as fluvial, deltaic and shallow marine deposits.Currently, adeep-water exploration of large scale has been launched in the northern South China Sea.How to correctly understand the deep-water gravity-flow deposition shows its significance.However,the petroleum exploration lacks the practical experience in the deep-water gravity-flow deposition exploration in our country, and the understandings regarding to the deep-water gravity-flow deposition are different.For example, deepwater gravity-flow deposition have to be deposited at certain water depth; identification of deep-water deposits must request deep-water environment marking; the strata sedimentary bedding structures caused by deep-water sedimentary process must have gravity flow pattern and so on.According to the drilling data and the study of sedimentary systems of the northern South China Sea, the features of the deep-water gravity-flow deposition win be described as event-trigger mechanism, transportation along the slope, deposition in low places, and limited distribution.The coarse continental clastic matter deposits outside the continental shelf break show the genesis of gravity flow sediments and sandstone reservoir developed easily in low stand system tract of gravity flow.the key of the deep-water exploration is the reservoir identification, which characterized by continental slope deep-water deposits.