In order to study the reasons for and mechanisms of deterioration of stone sculptures at Mao Mausoleum, we characterized the contaminants and soluble salts collected from the sculpture surfaces using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) and Fourier transform infrared spectrometry (FTIR), and also determined the ions of soluble salts and quantified their distribution using ion chromatography (IC). The results show that 1) gypsum crusts (CaSO₄·2H₂O) on “Horse Stepping on a Hun Soldier” was formed either by chemical reactions occurring on the sculpture surface due to deposition of atmospheric pollutants, or by capillary migration of soluble salts from underground water; 2) soluble salts containing Na₂SO₄, NaNO₃ and CaSO₄·2H₂O on the surface of “Monster Preying on a Sheep”, were mainly caused by capillary migration of soluble salts of underground water through the brick base to the stone matrix, resulting in repeated crystallization and dissolution on the sculpture surface according to environmental cycles of temperature and humidity. Soluble salts are known to cause stone deterioration in the form of lifting spalls, detaching scales and breakage of the internal material structure of stone sculptures. These are also the main diseases seen on the stone sculptures at the Mao Mausoleum.