As in other mammals, the gut of non-human primates (NHPs) contains a complex bacterial community, which plays an important role in host nutrition and health. Studies of the gut bacterial community of NHPs bear both ecological and conservation significance. During the last decade, the knowledge on the gut bacterial community of NHPs has been rapidly accumulated due to the development and application of molecular methods. In the present article, we reviewed the recent findings on the gut bacterial composition and its four major influencing factors of NHPs. Previous studies have shown that in general, the bacterial community in the gut of NHPs is mainly composed of the members from 12 phyla, among which Bacteroidetes, Firmicutes, and Proteobacteria are the predominant. These bacterial phyla contain numerous taxa at the lower taxonomical levels, and the similarities in the gut bacterial composition among different NHPs appear to be much lower at the family and genus levels than at the phylum level. Some families and genera account for particularly high proportions of the gut bacterial compositions in some NHPs species, and these bacteria are usually closely associated with food degradation of their hosts. The gut bacterial composition of NHPs is strongly influenced by host species and phylogeny, diet, age/sex, and social interactions. In the end, this article proposed several research aspects related to NHPs gut bacterial community that wait for future investigations. This review may contribute to the improvement of research on the gut bacterial community of NHPs in China, where such studies have relatively lagged behind.