The Bohai Bay Basin, situated along the eastern lacustrine margin of China, primarily developed during the Paleogene period. Its petroleum geological evolution can be categorized into three stages: continuous subsidence (energy accumulation), overall uplift (energy release), and shrinkage adjustment (energy redistribution). This chapter takes the Jiyang Depression as a case study to provide a detailed analysis of the Paleogene Shahejie Formation. Key topics covered include its depositional environment, paleontological features, stratigraphy, sedimentary facies characteristics, and primary source rock properties. These insights are essential for understanding the petroleum generation conditions and assessing the resource potential of the Paleogene in the Bohai Bay Basin.