According to their depositional characters, the reservoir/cap assemblages in the northern and southern continental marginal basins of South China Sea can be grouped into four types: continental sandstone + local cap, paralic sandstone +local or regional cap, neritic clastic sandstone/ carbonate/ biological reef + regional cap of neritic shale and clastic rock of deep water/neritic sandstone + cap of shale of deep water. The results of this study suggest that tectonic activity is the first controlling factor of the differences of reservoir-cap assemblages between the northern and the southern continental marginal basins. Evolution of regional geology and environmental settings are also important.