Abstract: The complex sandwich construction of lacustrine shales significantly influences the initiation and propagation of hydraulic fractures. The case study deals with lacustrine shale reservoirs of the Jurassic Lianggaoshan Formation in the Sichuan Basin. It uses half-diameter core samples with typical interlayers for high-resolution mechanical characterization via continuous scratch and impulse hammer tests. Based on the distinct distribution characteristics of key mechanical parameters (including uniaxial compressive strength and Young’s modulus) for the shale matrix and three interlayer types (shell, sandy, and argillaceous), artificial rock slabs with different mechanical properties are prepared using Portland cement as the binder with adjusted aggregate proportions. Following the similarity principle of physical modeling, cubic layered physical models with sandwich structures are constructed. True triaxial hydraulic fracturing experiments on physical models with three interlayer types show markedly different spatial distributions of hydraulic fractures. Further analysis of Mohr's circles and shear strength suggests that interlayers significantly control hydraulic fracture propagation pathways and fracture network complexity.