Shale oil is considered a crucial unconventional hydrocarbon resource. Its efficient development is significant for energy security. Strong heterogeneity and complex fracture networks in continental shale reservoirs are key geological factors that restrict their development. The Paleogene Shahejie Formation shale in the Dongying Sag, Bohai Bay Basin, develops millimeter-scale laminated structures, which provides an ideal condition for studying the coupling relationship between laminae and fractures. Taking the laminated shales of the Lower Es3-Upper Es4 sub-members as the research object. Core observation, petrographic analysis, and fluid inclusion techniques were comprehensively used. The types, characteristics, and formation mechanisms of natural fractures were systematically studied. The results show that shear fractures, bedding-parallel fractures, and two types of overpressure fractures (bedding-parallel and cross-lamina fractures) are developed in the study area. The bedding-parallel fractures are filled with fibrous calcite and parallel to the laminae. They are closely related to early hydrocarbon generation overpressure. Hydrocarbon inclusion data, including fluorescence spectral parameters (mean λ_max=584 nm) and homogenization temperatures (72.0~90.1 ℃), indicate they formed during the early maturity stage of oil generation. In contrast, the cross-lamina fractures crosscut the laminae and are typically filled with a mixture of bitumen and calcite. Their hydrocarbon inclusions show a λ_max mean of 517 nm and higher homogenization temperatures (85.4~113.2 ℃). They indicate formation during the peak hydrocarbon generation period of higher maturity, later than the bedding-parallel fractures. The differential distribution patterns of hydrocarbon generation and expulsion fractures in laminated shale are revealed. A three-stage fracture evolution model is established. The model is “tectonic shear fractures-early hydrocarbon generation overpressure bedding-parallel fractures-late hydrocarbon-generation overpressure cross-lamina fractures”. The understanding of the formation mechanisms of fracture network driven by overpressure is deepened. This work can provide a reference for prediction of shale oil “sweet spots” and optimizing hydraulic fracturing design.