There is a need to discover additional kinds of intestinal microbiota to supplement the probiotic-treatment of postmenopausal osteoporosis. Increasing evidence has indicated that Bacteroides vulgatus has potential as a probiotic for ameliorating postmenopausal bone loss. In this study, ovariectomized female C57/BL6 mice were treated with B. vulgatus ATCC 8482 gavage to investigate the differences in colonic microbiota composition, inflammation signal pathways, inflammatory cytokines, bone turnover markers, and lumbar vertebrae microstructure compared with the control group. Our results show that B. vulgatus ATCC 8482 diminished microbiota dysbiosis and subsequently down-regulated the colonic lipopolysaccharide/TLR-4/p-NF-κB pathway leading to decreased serum TNF-α. This reduced TNF-α/RANKL expression and induced ALP and Runx-2 expression in the 5th lumbar vertebra, leading to amelioration of bone loss and microstructure destruction in the lumbar vertebra of ovariectomized mice. Taken together, these results indicate that B. vulgatus could be a probiotic for treatment of postmenopausal lumbar osteoporosis.