Abstract: Objective: The aim of this study was to investigate the effect of lacidophilin on inflammation and intestinal microflora in H. pylori-induced gastritis mice. Methods: Established an H. pylori-infected mice model by orally administering an H. pylori suspension. The mice were randomly divided into a model group and a lacidophilin treatment group, which received treatment for four weeks. Gram staining, Warthin-Starry silver staining, and H. pylori immunohistochemical staining were conducted to confirm the colonization of H. pylori in the gastric mucosa of mice. Hematoxylin and eosin (HE) staining was performed to observe any histopathological changes in the gastric mucosa of mice. Immunohistochemistry was carried out to observe the expression of iNOS, IL-1β, and 3-Nitrotyrosine in the gastric mucosa of mice. Additionally, the structure of intestinal microflora was analyzed using 16S rRNA sequencing. Results: The successful establishment of H. pylori-infected mice. Lacidophilin improved the stomach histopathological morphology in mice with H. pylori-induced gastritis and inhibited iNOS, IL-1β, and 3-Nitrotyrosine expression in the gastric mucosa. The composition and structure of the gut microbiota among the lacidophilin group showed noticeable differences in comparison to the H. pylori-infected group. Lacidophilin augmented the diversity of intestinal microflora in H. pylori-infected mice by regulating the abundance of Firmicutes, Actinobacteriota, Bacteroidete, and Verrucomicrobiota. At the genus level, Lacidophilin resulted in significant growth stimulation of beneficial bacteria such as g_norank_f_Muribaculaceae, Akkermansia, and Alistipes, while suppressing the proliferation of inflammation-related bacteria such as Dubosiella, thereby improving the composition and structure of the gut microbiota. Conclusion: Lacidophilin has the potential to rebalance the composition and structure of gut microbiota that has been compromised by H. pylori infection. It may have a protective effect on mice with H. pylori-induced gastritis by promoting the growth of beneficial bacteria, reducing inflammatory reactions, and alleviating oxidative damage to the gastric mucosa.