Abstract:  [Objective] Deep shale reservoirs are characterized by high temperature, high pressure, and abundant bedding structures. During hydraulic fracturing, the mechanical properties of shale vary with thermo-mechanical conditions, while bedding heterogeneity further induces pronounced anisotropy. [Methods] Using a high-temperature triaxial rock mechanics testing system combined with CT scanning, ultrasonic measurements, and nuclear magnetic resonance, this study investigates the elastic-plastic deformation, failure behavior, and anisotropic features of bedded shale under high-temperature and high-pressure conditions were systematically investigated. [Results] The results demonstrate that thermal stress promotes the expansion of bedding structures, induces thermally driven microcracks, and reduces the mechanical strength of deep shale. Comprehensive analyses based on the Mohr–Coulomb, Hoek–Brown, and Drucker–Prager yield criteria reveal that, under elevated temperature and pressure, shale cohesion decreases while the internal friction angle increases, exhibiting more significant elastoplastic characteristics. Fractal dimension analysis, energy dissipation assessment, and damage factor calculations further indicate that thermal effects intensify rock damage and enhance the complexity of fracture networks. Anisotropy index evaluation shows that thermal stress amplifies shale anisotropy, whereas confining pressure partially suppresses the anisotropic differences in compressive strength and elastic modulus. [Conclusion] In summary, high-temperature and high-pressure conditions reinforce the elastoplastic deformation and failure modes of deep shale and markedly alter the anisotropy associated with bedding orientations. [Significance] The research outcomes will provide a solid mechanical foundation and reliable theoretical support for the development of deep shale reservoirs and the optimization of hydraulic fracturing engineering.