To explore the characteristics of surface hollowing and deterioration of historical sandstones, the sandstones of Xi Huang Si Temple were selected as a research subject. Chemical analysis, X - ray and scanning electron microscopy were used to characterize the chemical and mineral components and microstructure of the surface hollowed stone samples. This work revealed the primary causes of hollowing of the sandstones. The first is the existence of a schistose texture in the sandstone and a great amount of expandable clay or plaster sheets. Second, the surfaces of the stone dissolve under the effect of rain, allowing moisture to enter the interior of the sandstones. Inside the sandstone, the parts having a high content of clay or plaster expand rapidly with water, resulting in high pressure expansion. Third, at the locations where the clay or plaster content is high, the coupling strength is low. Hollowing occurs under expansion pressure. This test methods used and hollowing mechanism proposed can provide reference for similar studies.