Bacteroides is a group of promising candidates that has attracted major attentions from scientists as model organisms or community for the investigations of the intestinal microbiota field, due to their powerful adaption characteristics in the host and especially the underlying benefits. Bacteroides is a genus of Gram-negative, obligate anaerobic bacteria. Bacteroides species are non endospore-forming bacilli, and may be either motile or nonmotile, depending on the species. Bacteroides; order is the most abundant group of Gram-negative bacteria which flourish in the human intestine at high densities of 109-1011 CFU per gram of feces, and constitutes over 30 species which are more closely related than members in other bacteria orders. And, Bacteroides is considered as one of the major genera of the core microbiota module, of which species with relative abundance of over 1% refers to B. uniformis, B. vulgatus, B. caccae, and B. thetaiotaomicron. In addition to the unique physiological characteristics and the special ecological dynamics, Bacteroides species are under investigations for their underlying beneficial dialogues with the host. Bacteroides species to be considered as next-generation probiotics, and the application of which in prevention or intervention in dysbiosis of gut microbiota and the associated disorders requires further investigations in the modulatory mechanisms and safety evaluation. Bacteroides is one of the dominant contributors of SCFA among the intestinal commensals, mostly in the form of acetate and propionate. Accumulated acetate blocks the transportation of toxins between gut lumen and blood, while propionate is capable of inducing the apoptosis of human colon carcinoma cells, and thus avoids the formation of tumors. Moreover, Vitamin K, which is mainly synthesized by gut microbiota candidates such as Bacteroides, can help prevent or treat osteoporosis by increasing bone mineral density.