Abstract: Abstract: The developmental characteristics of hydrocarbon source rocks in deepwater basins abroad show that hydrocarbon source rocks are distributed at the stage of rifting and depression in both rifting-depressing or rifting-drifting basins. Effective source rocks have different development characteristics at different evolution stages of continental margin basin; of these rocks, non-marine (lacustrine) dark shale at the stage of rifting is the main and most common source rock. It is also possible to develop coal measures and muddy source rocks of transitional facies and paralic facies. With the supply of large quantities of organic matter of marine-continental transitional facies, paralic facies and prodelta facies at the late intraplate depression and under the margin-plate drifting condition, or in the circumstance of being long close to provenance, hydrocarbon source rocks would develop well. Source rocks do not develop at the late stage of rifting and the early stage of depressing. As a matter of fact, effective source rocks may develop under the condition of the supply of large quantities of organic matter from the semi-closed shallow sea and bathyal environment. The above characteristics have important guiding significance for the development of source rocks in northern South China Sea, where the main source rocks are lacustrine source rocks at the early rifting stage and marine-continental transitional facies source rocks at the late stage of rifting. Miocene marine source rocks vary in different basins. With enough terrestrial organic matter supply, source rocks from the Peal River Mouth basin is more effective than those from the Qiongdongnan basin. The exploration of Gulf of Mexico basin and northern Sumatra basin has proved that source rocks of bathyal facies seem to be effective source rocks, and this finding is of reference significance for the study of Miocene marine source rocks in northern South China Sea.