Abstract: The weathering of stone cultural relics is a difficult and important problem in cultural heritage conservation. Dry-wet cycles significantly accelerate weathering damage, leading to pulverization, exfoliation, and even complete disintegration of the rock. To reveal the chemical damage mechanism under dry-wet cycling, a multi-field and multi-phase coupled damage mathematical model was constructed using the argillaceous siltstone of the Longyou Grottoes as an example. The physicochemical processes of capillary water intrusion, water release, and calcite cement dissolution during dry-wet cycles were reconstructed by finite element simulation. The results indicate that during dry-wet cycling, the pore fluid undergoes a gas-liquid two-phase transition. The water absorption process is relatively rapid, with a wetting front parallel to the water immersion boundary, while water release is slower and pore water cannot be completely drained by gravity alone. With pore water intrusion, calcite cement dissolves into solution, and the pore water concentration inside the rock exceeds that at the surface, leading to differential chemical damage. The dry-wet cycle process renews the pore fluid and enhances its erosive capacity. Therefore, increasing the number of cycles promotes the overall damage rate and increases damage heterogeneity.