Nature reserves have played significant role in conserving China's animal biodiversity, particularly nonhuman primates. The strategies and management of the reserves to be periodically modified according to new circumstances. Thus, assessment of conservation performance is as important as setting up conservation strategies and management. This project assesses conservation sites of the François' Langur (Trachypithecus francoisi) in Yezhong Nature Reserve established in Guizhou province in 1987. The langur population has grown very slowly in this reserve over the past 30 years (from 73 in 1987 to 119 in 2016), falling short of increases in three other reserves established for the species. The relatively small area (2700 ha) of the reserve, particularly the core area which occupies only 22.4% percent of the area, is one factor that may have constrained population increase. Conservation measures must be implemented to establish a more favorable and sustainable relation between socioeconomic development and wildlife protection in order to save the species in this reserve.