Abstract: The North Jiangsu Basin and the South Yellow Sea Basin are a unified Mesozoic-Cenozoic basin.The North Jiangsu Basin has seen fruitful exploration. Four out of seven sets of dark mudstone only contribute to hydrocarbon accumulation by geochemical analysis, in which three are wide lacustrine lime mudstones in depression which is characterized with wide distribution, high quality and significant in lithology-electricity, the other one is pure mudstone in rift lake. It can conclude that there are 5 sets of source rocks in the Southern Depression which are more in numbers and slightly larger in thickness than in the North Jiangsu Basin, and only one in the Northern Depression of the South Yellow Sea Basin. The source rocks of the South Yellow Sea Basin are similar in original environment and lithology-electricity with the North Jiangsu Basin, but less in quality and continuity. Source rocks develop at the low mature-mature stage in two basins, of which the South Yellow Sea Basin is lower in maturity than the North Jiangsu Basin resulting to narrow distribution of expulsive petroleum source rock. Quality, maturity and degree of expulsion of source rocks dominate abundance of hydrocarbon resources in sags of the North Jiangsu Basin, higher maturity and hydrocarbon expulsion of source rock, higher abundance of resources, otherwise it is low. Deeper sediments are buried in rift sag, more mature in source rocks. The end of the Sanduo stage is time for complete maturity of source rocks. In general, the South Yellow Sea Basin is not larger than the North Jiangsu Basin in resource potential where the Southern Depression is better than the Northern Depression.