Abstract: In order to study the effect of acidic environment on the corrosion and deterioration of rocks, CT images processing technology was used to analyze the meso-composition and structural changes of feldspar sandstone after soaking in acidic water. Shimadzu AGI-250 servo material testing machine was used to carry out uniaxial compression test to observe the deterioration of mechanical parameters. The results show that the total density of the feldspar sandstone decreased Ofter the acidic environment treatment, the distribution trend is homogeneous, and the mineral with higher density is formed in the local area. The secondary pores of the feldspar sandstone increased after the acidic environment treatment. The change of the external pore could be seen directly. The internal pores changes could be directly reflected by the minimum circumscribed rectangle area. The maximum decrease in compressive strength, elastic modulus, and peak strain of feldspar sandstone treated in acid water reached 34.092%, 22.016%, and 13.705% respectively. The degradation degree of the strength parameters was higher than that of the deformation parameters. When there was sufficient H⁺ in acidic water, the dissolution reaction of sandstone in acidic solution was mainly. After the H⁺ was reduced to a certain extent, orthoclase and plagioclase dissolved, and other authigenic minerals could be formed. When H⁺ was consumed, the reaction proceeded mainly by hydrolysis. By applying the combination of CT images processing technology to the mechanism analysis of mechanical properties of sandstone after acid environment treatment, a new idea and method for studying the composition and properties of heterogeneous materials such as rock is provided.