Objective：To investigate the role of Bmi-1 in preventing atrophic gastritis in mice. Methods：The phenotype of stomach was compared between wild-type and Bmi-1 gene knock-out mice at 7 weeks of ages by histology，immunohistochemistry and Western-blot. Results：Bmi-1 gene knock-out mice displayed thin gastric wall，inflammatory infiltration in gastric mucosa and atrophy of gastric gland. The expression of interleukin-6（IL-6），tumor necrosis factor α（TNF-α） and nuclear factor-κB-p65（NF-κB-p65） is up-regulated in Bmi-1 knock-out mice. Conclusion：Bmi-1 could protect mice from atrophic gastritis by down-regulating NF-κB signaling pathway.