From January 25th to August 24th, 2013, the population size of Rhinopithecus brelichi was investigated by the method of sampling line survey by setting up 30 sampling lines in Fanjingshan National Nature Reserve. The survey results show that the Rhinopithecus brelichi is only distributed in the nature reserve currently with the altitude 900 to 2180 meters above sea level, and the population size is 661 to 710. A total of 94 "family groups", 94 adult males, 315 adult females, 74 sub-adults, 83 young individuals and 95 infants were enumerated when they were clearly enumerated. The Rhinopithecus brelichi acts as a group structure, mainly active in four regions in the Fanjingshan National Nature Reserve. Each group consists of 2 to 10 family groups with the smallest family size consisting of 1 male and 1 female. The common family group consists of 1 adult male and 2-4 adult female individuals, and Sub-adult individuals, young individuals and infants. During annual April to May and September to October, the fusion group gathering activities will appear with more than 300 individuals for short-term activities, indicating that these time periods could provide the best opportunities to study the Rhinopithecus brelichi.