Due to the influence of acid rain, many historical stone inscriptions and natural sceneries suffer from deterioration in the exposed carbonate rock area of southwestern China. In order to have an insight into the surface dissolution of carbonate rock, saturations of the rain samples are analyzed by the common used hydrogeo-logical simulation software PHREEQC and the dissolution surfaces of the carbonate rock test pieces are observed by the scanning electron microscope (SEM). Results from the present investigation suggest that the variation ranges of saturation index of calcite 5/(cal) and saturation index of gypsum S/(gyp) are much the same,variation range of saturation index of dolomite S/(dol) behaves in a greater extent although its magnitude is always lower than the two indexes above. The dissolution capacity of acid rain refers to its initial state and the reaction duration. The surfaces of carbonate test pieces also exhibit different micromorphological characteristics under the acid rain with different saturations. In weak acid rain crystal edge comers are comparatively clear, with a small harbor-like corrosion border. Intergranular pores are almost intact while in strong acid rain the erosion trace becomes obvious, cracks take shape of larger intergranular pores with obvious residues. Small particles of calcite intergranular pores are contiguous because of corrosion. Part of intergranular pores are contiguous together because of corrosion. Some crystal edge corners are dissolved, with harbor-like corrosion border residues, bean-like residues in part of deep dissolved pores.%通过水文地球化学模拟软件PHREEQC对雨水样品进行饱和度分析,再通过扫描电镜(SEM)对石灰岩溶蚀试片表面进行观察.研究结果表明:(1)方解石饱和指数SI(cal)和石膏饱和指数SI(gyp)的变化范围大致相同,白云石饱和指数SI(dol)的变化范围比较大,但其数值始终低于前两者,说明酸雨溶蚀能力与其初始状态和作用时间有关；(2)不同酸碱度酸雨的作用下,石灰岩试片的表面也呈现不同的溶蚀微形态特征:弱酸雨情况下方解石晶体棱角较为清楚,有少量港湾状的溶蚀边,晶间孔基本保留完整；强酸雨情况下溶蚀痕迹加剧,裂隙变大,形成较大的晶间孔,残留体较为明显,方解石小颗粒晶间孔溶蚀连成片；灌木丛下溶蚀痕迹介于两者之间,部分晶间孔由于溶蚀扩大连在一起,晶体棱角部分被溶蚀,港湾状溶蚀边较多,残留体较微小,溶孔较深,局部间有豆状残留体.
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