<p>Coal-seam water-injection technology (CSWI) effectively mitigates coal and gas outbursts. The complex pore-fracture structure causes non-uniform water distribution, with bedding structures further intensifying this feature. The damage evolution law of this non-uniform water distribution on coal body is unclear, and the damage constitutive model (DCM) has not been established. In this study, coal samples with horizontal and vertical bedding were selected for spontaneous imbibition (SI) experiments. Uniaxial compression test and acoustic emission monitoring are used to reveal the damage evolution law during the SI process. The strain energy theory is used to analyze the energy dissipation characteristics, and the DCM of coal was developed by defining the imbibition damage factor. The results showed that the uniaxial compressive strength, elastic modulus, and cumulative ring count exhibited a negative correlation with water content, and the attenuation rate of coal samples with vertical bedding is usually 2–3 times that of horizontal bedding. The nonuniform distribution of absorbed water imparted a certain water-sensitive directionality to crack propagation. In coal samples with vertical stratification, the proportion of tensile cracks decreased as water content increased, whereas the opposite trend was observed for coal samples with horizontal stratification. An increased water content led to a reduction in the ultimate elastic energy of the coal matrix voxels and an increase in the relative dissipated energy. In addition, the DCM effectively fits the stress change behavior of coal during SI process, offering a theoretical foundation for predicting coal damage and applying CSWI technology.</p>