Abstract: There are huge reservoirs in the northern shelf basins of South China Sea, in which more than 1/3 are non-structural subtle reservoirs. Therefore how to exploit these subtle reservoirs with reason is an important matter for our marine petroleum in the future. The main types of subtle reservoirs in the north of South China Sea are lithologic reservoir, stratigraphic reservoir, burial hill reservoir and diapir reservoir. The upgrowth depositional systems of these subtle reservoirs include submarine fans, slope fans, shelf margin deltas and carbonates rocks. Thus we must know the upgrowth environment and further recognize the reservoir mechanism for exploiting and exploiting completely the subtle reservoirs in the north of South China Sea.