Grooming behavior is one of the social behaviors commonly found among primates. Such behavior is often associated with particle removal, with the groomers manually brushing away, or sometimes devouring, loose particles . However, the function of allogrooming and the associated particulate matter still remain controversial. In this study, we used all occurrence sampling to record autogrooming and allogrooming behaviors in captive Sichuan snub-nosed monkey (Rhinopithecus roxellanae) in the Endangered Animal Breeding Center of the Beijing Wildlife Park from February to Match 2017. A total of 120 bouts of autogrooming and 259 bouts of allogrooming were recorded to test the hygienic functional hypothesis and the compensation hypothesis of allogrooming. The particulate matter on the hair and skin was checked for ectoparasite, flakes of skin or secretion of salt using microscopy. In addition, we manipulate salt and protein intake via offering the monkeys with drinking water of different concentrations of salts and fresh Populus leaves with high protein, in order to test the nutritional function of allogrooming and particle intake. Our results suggested that the grooming behaviors of the monkeys in general were consistent with the prediction of hygienic functional hypothesis, but in adult males, but not in adult females, were broadly in line with the prediction of compensation hypothesis. No association was noted between grooming and removal of parasites, and neither the functions of obtaining protein, or sodium chloride were confirmed. In conclusion, grooming behavior of captive Sichuan snub-nosed monkeys is more likely to be a semi-ritualized social behavior.