In order to study the mechanical strength deterioration characteristics of the stone site under the effect of water saturation and to determinethe seepage and migration path of groundwater, lab micro-tests, macro-tests and field seepage tests are comprehensively conducted on multiple scales. The microscopic tests include polarized light microscope (PM), X-Ray diffraction (XRD) and porosity test, the macroscopic tests include water absorption test and uniaxial compressive strength softening test, and the on-site testing mainly adopts high-density resistance method to image and analyze the water-bearing rock layer. The petrographic identification results show that 1) the overall lithology is sandy mudstone, and the mineral composition is mainly of quartz and feldspar. Illite is the main clay mineral. This kind of rock has poor resistance to wetting and drying cycle. The saturation coefficient of sandy mudstone is between 0.84~1.00, and the softening coefficient is between 0.55~0.65, indicating a soft rock, and its high softening is the main reason for the deformation of formation structure. 2) Under the action of surface water, the mudstone is exposed and tectonic fissures are formed, some rock surfaces are sabjected to salt precipitation problem, and the slope is unstable and deformed under the coupling action of seepage and stress. The field detection of high-density resistivity method shows that the groundwater leakage leads to a low resistance zonebelow, and the resistivity is below 20 Ω·m, which is mainly caused by seepage of the canal.