The shale samples were collected from QY1 and QY3 wells in the second member of the Paleogene Funing Formation of the Qintong Sag, Subei Basin, China, to investigate the oil-bearing characteristics of the shale series. The samples were subjected to comprehensive analysis using techniques such as electron microprobe, X-ray diffraction, argon-ion polishing coupled with scanning electron microscopy, pyrolysis analysis, and confocal laser scanning microscopy. It is found that the mineral composition of the shale in the second member of the Fu-formation is notably complex. The pore structure is predominantly comprised of nano-scale micropores, forming an intricate pore network. The results indicate that subsections Ⅰ and Ⅱ exhibit markedly higher oil contents and greater oil potential than subsections Ⅲ and Ⅳ. Further analysis shows that the distribution of light and heavy components within the shale oil is influenced not only by the mineral composition but also closely correlated with burial depth. Additionally, the occurrence of shale oil is significantly impacted by the level of maturity. Shale oil is primarily concentrated within felsic/gray striations in high maturity samples, while it is mainly stored within muddy striations in low maturity samples. It is established that shale oil predominantly occurs in shales with medium to high maturity. These findings provide a crucial theoretical foundation for the exploration and development of shale oil resources in the Qintong Sag.