Abstract: Shale oil reservoirs are typical unconventional oil and gas reservoirs with complex mineral composition. The types and distribution of mineral particles have an important impact on the propagation of hydraulic fracture in shale oil reservoirs. The research object is a continental shale oil reservoir, Lucaogou Formation of Jimsar Sag. In order to achieve an intensive study of the hydraulic fracture propagation law of deep shale oil reservoirs under hydraulic fracturing, digital rock cores were constructed based on the scanning images of 20 groups of shale samples within the depth range of 3684.62 m to 3705.70 m. Moreover, hydraulic fracturing numerical experiments of the digital rock cores were carried out. Scanning electron microscopy and energy spectrum analysis were utilized to analyze the mineral composition and to gain the mineral distribution figures. Realistic failure process analysis (RFPA) based on the finite element method was applied to build the digital rock core and model the hydraulic fracturing process. The breakout pressure and hydraulic fracture geometry of each model were discussed. The results show that mineral composition and porosity have an important impact on the breakdown pressure, hydraulic fracture initiation and extension, and complexity of hydraulic fractures in shale oil reservoir. The breakdown pressure increases with the increase of brittle mineral content (quartz, calcite and dolomite) and shows a more obvious linear relationship with quartz content because of quartz's high strength. The breakdown pressure decreases with the increase of porosity. Pores weaken the strength of shale and offer seepage shortcuts for fracturing fluid. The initiation and extension of hydraulic fractures are mainly affected by the in-situ stress and pore distribution. Hydraulic fractures initiate from the pore near perforation, connect independent pore regions and propagate along connected pore regions. In the areas far from pore regions, hydraulic fractures extend along directions perpendicular to the minimum principal stress. The complexity of hydraulic fractures in shale increases with quartz content and porosity but is also affected by the distribution of minerals. When hydraulic fractures encounter quartz minerals, they extend through or bypass them. When bypassing quartz minerals, hydraulic fractures form branched fractures and the complexity of fracture geometry increases. When the quartz content or porosity is high and presents a large area of connected distribution, the expansion of hydraulic fractures is inhibited. Large particles of quartz mineral dramatically increase the brittleness and breakdown pressure of the rock, inhibiting the formation of a complex fracture network. The connected pores form high-density lamellation causing a large amount of filtration of fracturing fluid, resulting in low stimulated efficiency and permeability enhancement.