To explore the evolution law of mechanical properties of disintegrating mudstone under dry-wet cycles, the disintegrating mudstone in the northern part of Guangxi was taken as the research object. Uniaxial compression tests and scanning electron microscopy tests at the same position were carried out under different dry-wet cycle numbers. The deterioration law of physical and mechanical parameters, energy evolution law and microstructure change characteristics of mudstone under different dry-wet cycle numbers were analyzed, and a statistical damage constitutive model considering the residual strength of mudstone was established. The results show these as follows. After 5 cycles, the mass loss rate of mudstone reaches 12.9%, the longitudinal wave velocity, uniaxial compressive strength and elastic modulus decrease by 77.9%, 82.1% and 76.2% respectively, and the failure mode changes from shear failure to ductile failure with multiple shear bands. Microstructure analysis shows that the cementation material softens and fractures due to the water-hydration-drying cycle, and the development of micro-pores and particle shedding in mudstone are positively correlated with the number of dry-wet cycles. Based on the energy dissipation evolution law, a four-stage damage development model is proposed, revealing that the elastic strain energy storage capacity of mudstone decreases exponentially with the number of dry-wet cycles. Based on the Weibull distribution and the maximum tensile strain criterion, a damage statistical model considering the residual strength correction is constructed, achieving high-precision characterization of the post-peak residual strength stage (R²>0.9). The research results provide a theoretical basis for the long-term stability study of disintegrating mudstone slopes in the northern part of Guangxi.