Abstract: The scotch shallowing, cracking, exfoliation, solution and other diseases directly related to the damage of rock surface weathering are highly developed, which are the important reasons for the damage of Helan Pass petroglyph. In this study, those samples immersed in different solutions, and systematically explored the damage characteristics of metamorphic sandstone surface crust under different coupling effects of freezing-thawing, drying-wetting and chemical dissolution. Then, the study reveals differential damage mechanism between rock surface weathering crust and original rock by comparing the damage variables, XRD and SEM analysis results under the same deterioration condition as the original rock. The results show that the mass, surface hardness, flexural strength and stress-strain characteristics of the samples generally show a law of gradual differential attenuation with the increase of the number of cycles, and the change rate presents three stages, with two obvious inflection points of 45 times and 90 times. By comparing the damage variables of rock surface weathering crust and original rock, it is found that the damage inflection point of rock surface weathering crust lags behind and the damage rate is faster than that of original rock, the essential difference of the damage mechanism between the rock surface weathering crust and the original rock is that the porosity of the rock surface weathering crust is larger than that of the original rock and the differential combination of hydroxylation, chemical dissolution of single plagioclase and salt crystallization and dissolution, that results in a rapid increase in the number and connections of linear pores and pores in the rocks, this difference provides evidence for the high development of petroglyph's diseases such as scotch shallowing, cracking, exfoliation and solution.