The southern regions of China host a substantial number of open-air limestone cultural relics. Limestone, primarily consisting of CaCO3 (calcite), is highly susceptible to dissolution, making the physical environment a critical factor in the preservation of these relics, particularly in high-humidity environments containing sulfur oxide gases. To simulate and assess the dissolution risks of limestone relics under fluctuating thermal and humidity environment, this study take the Yangshan Stele as an example. A heat and moisture transfer model was devoloped to simulate the thermal and humidity distribution across various parts of the stele's surface. The relative humidity of these points at different positions on the surface of the stele were calculated and if they were in a high humidity the state was further evaluated. The simulation results show that the proportion of the annual time of the Yangshan Stele in dissolution risk states is 0.39–2.89%. The annual dissolution time of the north and west facade is slightly higher compared to the other facades. The dissolution risk in January, February and June was high compared to other months. According to the Arrhenius equation, the reaction rate constant k of the dissolution reaction in summer is 1.89–2.04 times higher than that in winter. Therefore, we should focus on strengthening the daily monitoring and protection during the month with high incidence of dissolution, especially for the lower part of the body, the north and west facade.