Abstract: Aiming at the most unfavorable environment of marl in the fluctuating zone of the reservoir area—the problem of damage and deterioration of mechanical properties under dry-wet cycle in acid environment,taking bank marl as the research object,the dry-wet cycle tests under the condition of pH=3,5,7 solution were carried out respectively,the deterioration law of uniaxial compressive strength of marl under dry-wet cycle in acid environment was analyzed,and the damage deterioration characteristics of marl to mechanical properties were found out. The influence law of different cycle times on mechanical strength parameters is explored by using particle flow software,and the mechanism of stratification deterioration is analyzed in combination with the deterioration phenomenon of rock mass in the fluctuating zone of the reservoir area. The results show that the change of uniaxial compressive strength of marl in pH=3,5,7 solution is inversely proportional to the number of dry-wet cycles,and the cumulative deterioration degree S_n varies from 34.79% to 54.31%,and shows a trend of rapid increase,slow development and tends to be stable,while the range of peak stress deterioration is 8.79% ~35.61%. The cohesion C,internal friction angle φ and elastic modulus E of marl all decrease with the increase of the number of dry-wet cycles,and the damage deterioration is carried out in the progressive mode of circle layer. After the rock mass in the fluctuating zone of the reservoir area is subjected to the dry-wet cycle of acid solution,a large number of secondary cracks will sprout in the nearby rocks. with the advance of the number of cycles and the continuous accumulation of damage,the cracks gradually run through and expand to the inner layer of the slope. The expansion range and rate are related to the number of dry-wet cycles and the pH value of the solution. The above analysis conclusions and laws can provide scientific basis and theoretical methods for the prediction and emergency prevention of disasters such as collapse and instability of landslide,softening of dangerous rock base and water storage leakage in the reservoir area.