In order to thoroughly investigate the mechanical properties and fracture evolution mechanisms of sandstone containing weak interlayers during the failure process, triaxial acoustic emission tests were conducted on intact sandstone and sandstone with weak interlayers at different inclination angles (0°, 30°, 45°, 60°, and 90°). By comprehensively analyzing the acoustic emission ring-down counts, precursor characteristics of the b-value, AF-RA crack classification, and three-dimensional positioning distribution, the influence of the interlayer inclination angle on the failure characteristics of sandstone was studied.The results show that the presence of weak interlayers significantly alters the mechanical response characteristics of sandstone. The peak strength and elastic modulus of sandstone exhibit a U-shaped distribution pattern with respect to the interlayer inclination angle. Among them, the sandstone with a 60°-inclined interlayer has the lowest peak strength, which is 62.3% lower than that of intact sandstone, while the peak strength of sandstone with a 90°-inclined interlayer is close to that of intact sandstone. The variation pattern of acoustic emission ring-down counts reveals the differences in the failure modes of sandstone with interlayers. Sandstone with low- and high- inclination interlayers exhibits brittle failure characteristics due to through-going fractures, while sandstone with medium-inclination interlayers shows ductile characteristics as a result of shear-slip failure along the interlayer. Shear cracks dominate the crack propagation in sandstone, accounting for 63.3%~86.7% of the total. Cracks in sandstone with medium-inclination interlayers are densely distributed along the interlayer. In sandstone with a 90°-inclined interlayer, stress-arch-induced tensile failure occurs, and cracks are distributed both along the interlayer and near macroscopic fractures. A sudden drop in the acoustic emission b-value is observed before failure. For sandstone with a 30°-inclined interlayer, the warning time occurs 500 seconds before failure. The theoretical model based on the Mohr-Coulomb criterion indicates that sandstone with a 60°-inclined interlayer is most prone to instability due to the shear-slip effect. By using the semi-inverse method to perform analytical calculations on weak interlayers, the failure modes of sandstone under different working conditions can be predicted. It is concluded that the research findings can provide key parameters and analytical methods for the stability assessment and disaster warning of geotechnical engineering.