Abstract: The seepage effect of leaching solution in the process of in-situ leaching mining may lead to the deterioration of the mechanical properties of the aquifuge, and affect the safety of coal uranium co-mining. Taking the conglomerate aquifuge of Jurassic Zhiluo Formation in Inner Mongolia as the research object, the physicochemical properties and mechanical deterioration mechanism under acid leaching environment were discussed. The mass and metal cation concentration of tometer. The variation characteristics of mineral composition and microstructure conglomerate in sulfuric acid solution were measured by electronic balance and atomic absorption spectropho of conglomerate with immersion time were analyzed by XRD and SEM. Triaxial compression tests were carried out to study the mechanical response of conglomerate under different immersion time. The evolution laws of parameters such as peak stress, elastic modulus, axial strain and dissipation energy density were analyzed. The coupling relationship between mechanical parameters and physicochemical parameters was quantified based on correlation analysis. The results show that the mass of conglomerate first increases and then decreases with the acid etching time. The concentration of metal cations in the solution is consistent with the mass change trend, and the concentration of Ca²⁺ is the highest, indicating that the chemical reaction between calcite and sulfuric acid is an important factor leading to the deterioration of mechanical properties of conglomerate. Acid corrosion gradually dissolves the conglomerate cement, expands the internal fractures, and increases the pores, resulting in changes in the rock microstructure. The peak stress, elastic modulus and yield stress of the conglomerate increased briefly in the initial stage (1 d) and then gradually decreased. After 20 days of immersion, the peak stress decreased by 26.69% compared with the natural state, and the peak volumetric strain decreased significantly, indicating that the specimen changed from brittle failure to ductile failure mode. The growth rate of dissipative energy density in the post-peak stage presents the characteristics of “slow-fast-slow”, and the failure process of the specimen is more gentle under the action of long-time acid leaching. The peak stress, elastic modulus and total strain energy density have a strong positive correlation (r>0.8), and the metal cation concentration can be used as a characterization parameter for the deterioration of mechanical properties of conglomerate.