Gut microbiome gene catalogues have advanced the knowledge of host-microbiome interactions in many mammals. Snub-nosed monkeys (Rhinopithecus spp) are folivores with foregut fermentation which is similar to ruminants, but their gut microbiota lacks a comprehensive description. In this study, we constructed a comprehensive gene catalogue by performing metagenomic analysis on 143 wild snub-nosed monkeys and compare it to that of ruminants and monogastric animals. Our results demonstrate the classification and functional characteristics of the gut microbiome of snub-nosed monkeys and identified a set of core genera in these mammals. Moreover, we found that the gut of snub-nosed monkeys and other herbivores was enriched with more bacteria and enzymes related to the degradation of structural carbohydrates, indicating the importance of gut microbiota for dietary adaptation. Our study expands resources for gut microbiome studies of nonhuman primates and provide new insights into the evolutionary route of foregut fermenting animals during dietary adaptation.