Abstract: Geological survey and research data reveal that there are four sets of marine source rocks in the Mesozoic-Paleozoic of the Lower Yangtze Region. From the perspective of the abundance of organic matters, the four sets of hydrocarbons source rocks are all good enough for hydrocarbon generation. The lithofacies paleogeographic background indicates that the early Paleozoic argillaceous source rocks were mainly deposited in a deep water shelf basinal environment (the Lower Cambrian Mufushan Formation and the Lower Silurian Gaojiabian Formation), and the late Paleozoic carbonate source rocks deposited in a paralic environment (the upper Permian Longtan Formation), while the carbonate platform facies is deposited on a restricted platform (lower Permian Qixia Formation). The spatial distribution of sedimentary facies suggests that the favorable source rocks obviously occur in a tendency to extend to the south Yellow Sea. It means that the marine Mesozoic-Paleozoic in the South Yellow Sea Basin is favorable for hydrocarbon generation and accumulation.