Abstract: Siltstone, as one of the most widely distributed rock types on Earth, is frequently used in engineering projects. The increase in water content within argillaceous siltstone can lead to reduced rock strength and increased deformation, which in turn may result in geological hazards such as tunnel collapses and slope landslides. Therefore, understanding the fracture evolution of argillaceous siltstone under different water contents is significant. This study focuses on constructing a numerical model of the argillaceous siltstone surrounding the Longyou Grottoes. Using stress-strain curves and fracture morphology obtained from high-energy CT real-time scanning experiments under in situ loading conditions, the model parameters were calibrated. The dynamic fracture evolution process of argillaceous siltstone with varying water content under uniaxial compression was then simulated. Furthermore, the study uses acoustic emission and moment tensor inversion techniques to reveal the effects of different water contents on the fracture behavior of argillaceous siltstone. The research results indicate the following: (1)In terms of Argillaceous Siltstone Strength: As water content increases, the strength of argillaceous siltstone gradually decreases. However, once the water content surpasses 50%, the weakening effect of water on argillaceous siltstone strength diminishes. (2)In terms of AE Magnitude and b-value: With increasing water content, the b-value at failure also increases. This suggests that higher water content leads to a greater number of small-scale events during the fracture process, making the failure more gradual, less severe, and releasing less energy. (3)In terms of Fracture Morphology and AE Failure Sources: As water content rises, the proportion of AE shear failure sources gradually increases. The failure mode of the argillaceous siltstone transitions from single-plane shear failure to X-shaped conjugate shear failure. As the water content approaches saturation, the failure behavior is characterized by splitting-dominated exfoliation of the outer surface, coupled with internal shear failure.