Exploring the mechanical properties of soft-hard interbedded rock mass with different initial damage is crucial for assessing the stability of post-seismic damaged rock masses under cyclic drying and wetting conditions. This study focuses on the interbedded rock mass of metasandstone and phyllite, using an MTS rock testing machine, an acoustic emission system, and digital image correlation technology. Through cyclic loading and unloading tests followed by cyclic drying and wetting tests, the samples with different initial damage degrees were prepared. Subsequently, uniaxial compression tests were conducted to investigate the deformation and failure characteristics, crack evolution process, and strength degradation laws of samples with different initial damage degrees, explore the precursor information of sample failure, and reveal the damage degradation mechanism from a micro perspective. The results indicate: (1) Deformation on the surface of the soft-hard interbedded rock mass is not concurrent; the deformation of the phyllite layers exceeds that of the metasandstone layers, and the first signs of local high strain zones emerge. The deformation difference coefficient can quantify the discrepancies in deformation across different areas of the sample surface. A shift from a decreasing to an increasing deformation difference coefficient indicates that local cracks have coalesced. (2) The propagation of transcrystalline crack and intercrystalline crack extends throughout the loading process, with tensile fracturing being the primary mode of failure. During the plastic stage, shear fracturing characteristics become more evident, leading to an increase in the coefficient of variation (CV) of the RA/AF values. When the CV reaches 6.5, the sample is approaching failure. (3) The shear failure mode of the sample is primarily governed by the structural features of the rock mass, while initial damage influences the type of failure and the development of cracks. Higher initial damage degrees result in more microcracks and more pronounced shear fracturing characteristics. (4) Initial damage leads to a decrease in elastic modulus, compressive strength, and failure displacement. The increase in microcracks and the weakening of interparticle bonding are the fundamental causes of the deterioration of the rock mass's macroscopic mechanical properties.