Abstract Geophagy is widely reported in primates, and several functional hypotheses have been proposed to explain this phenomenon, including supplementation of minerals, adsorbance of toxic substances, anti-diarrhea effects, protection against parasitic infections in the body, and balancing the acid in the intestines and stomach. In order to improve our knowledge of impact factors and function of geophagy in golden snub-nosed monkey (Rhinopithecus roxellana), we collected diet and geophagy data on golden snub-nosed monkey via a scan-sampling at 5-mins interval, from Sept. 2013 to Jan. 2015 in Qinling Mountains. The site of geophagy, and the sex and age of individuals who were eating clay were recorded. We also collected samples of clay and control soil. The pH of the soil simples was measured using potentiometry in Jul, 2016. We found all individuals from different sex-age groups including infants ate soil. We also found that the clay had higher pH than did control soil. Therefore, our result suggested that golden snub-nosed monkeys consumed soil with higher pH, which may serve to balance acids in the intestines and stomach, A high frequency of clay-eating was coincident with high percent of bud and leaf in the diet.