<p>To elucidate the deformation response and underlying crack propagation mechanism of mudstone under complex disturbance conditions, uniaxial cyclic loading and unloading experiments on mudstone with different cyclic stress amplitudes (CSAs) were carried out in this study, with a focus on the crack propagation characteristics. Through acoustic emission (AE) monitoring and computed tomography (CT) scanning techniques, this study systematically investigated the deformation characteristics and crack propagation of mudstone under different CSAs. The results show that under low CSAs, the mudstone primarily underwent elastic deformation. In contrast, high CSAs markedly promoted crack propagation within the sample, which manifested as a decrease in the elastic modulus to 6.403 GPa and an increase in the dissipated energy percentage from 0.768 to 7.110% in the cyclic stage. Moreover, the significant increase in the AE low-frequency percentage from 72.44 to 82.31% and the decrease in the <i>b</i> value at high CSAs indicated that crack propagation gradually progressed to large scales. Additionally, the fractal features of AE counts indicated that the disorder and complexity of crack propagation increased significantly at high CSAs. This finding was further verified by CT scans, which showed an increase in the crack volume fraction from 5.694 to 14.873% and in the three-dimensional fractal dimension of the mudstone at high CSAs. Crack propagation and stress corrosion of mudstone driven by cyclic loading at high CSAs are more significant. This is primarily attributed to the tensile stress induced stretching of the silica network in clay-rich minerals, which facilitates chemical bond weakening, thereby accelerating microcrack evolution and damage accumulation.</p>