As an important outdoor cultural relic, the grotto temple is affected by the dry-wet cycles caused by rainfall, water seepage and other natural environment for a long time, As a result, the deterioration of physical and mechanical properties is induced, causing instability damage. In order to better protect grotto cultural relics, the sandstone of Dazu stone carving grottoes is selected as the research object. Experimental research on the strength deterioration characteristics of grotto sandstone under the action of dry-wet cycles is carried out through uniaxial compression test and Brazilian split test, and the influences of dry-wet cycles combined with immersion in solutions of different pH values are analysed. The results show that: (1) The uniaxial compressive and tensile strengths of sandstone after complete drying are improved compared to the natural state. (2) The mechanical properties of the sandstone deteriorate after several dry-wet cycles. With the increase of the number of cycles, the deterioration gradually increases. When the dry-wet cycle reaches a certain number, the impact on the strength of sandstone is weakened. (3) Different pH values also affect the degree of sandstone deterioration. The lower pH value will induce more serious deterioration of the sandstone mechanical properties. (4) After several dry-wet cycles using acidic solutions, the sandstone damage form changes compared to that in the natural state.