The shale hydration disturbance causes varying degrees of damage to the pore structure of surrounding rock of the borehole wall, deteriorates its mechanical properties, and reduces the safety and stability of the borehole wall. By using nuclear magnetic resonance (NMR) and triaxial compression test, the volume change and mechanical properties of rock samples versus different soaking time were tested and analyzed. Research results: (1) Through the increasing trend of signal intensity amplitude of T₂ energy spectrum, the transformation and expansion rules of pores with different scales are analyzed, the mechanical mechanism of shale hydration damage and failure is revealed, and the change rules of shale void ratio and volume expansion rate are analyzed. (2) Through the curves of shear strength and elastic modulus of shale changing with soaking time, the evolution law of shale strength decline is analyzed, which revealed that shale hydration has obvious timeliness. (3) Based on the test results of shale hydration disturbance damage, using damage mechanics and strength statistics theory, and taking the volume expansion rate as the investigation variable, a statistical damage model of shale hydration disturbance is established to predict damage evolution law of shale hydration disturbance. The research results have important guiding significance for practical engineering.