Helicobacter pylori (H. pylori) infection is the main cause of chronic gastritis, and dietary interventions with probiotics may inhibit H. pylori colonization. A mouse model of gastric H. pylori infection via oral gavage to explore the inhibitory efficacy of Lactobacillus plantarum 543, Lactobacillus paracasei S6, and postbiotics derived from Lactobacillus plantarum LP220 on gastric infection by H. pylori in mice was established. The gastric viable H. pylori count in the model group was 9.69 log CFU/g. Treatments with Lactobacillus plantarum 543, Lactobacillus paracasei S6, and postbiotics significantly reduced the respective viable H. pylori counts in mouse stomachs to 7.22, 7.89, and 7.19 log CFU/g (P<0.01). These three treatments also significantly reduced gastric mucosal thickness (P<0.05) in the model group and alleviated structural damage in gastric tissues. Additionally, the mRNA levels of H. pylori virulence factors and inflammatory factors including tumor necrosis factor-α (TNF-α) in gastric tissues were notably suppressed after treatments with Lactobacillus paracasei S6 and postbiotics, while this was not observed with Lactobacillus plantarum 543 exposure. In conclusion, Lactobacillus plantarum 543, Lactobacillus paracasei S6, and postbiotics all inhibit H. pylori infection, with Lactobacillus paracasei S6 and postbiotics demonstrating superior efficacy in mitigating gastric inflammation and reducing H. pylori virulence factor expression, compared to Lactobacillus plantarum 543. These findings provide new evidence supporting the use of probiotics and postbiotics as nutritional interventions to ameliorate chronic gastritis induced by H. pylori infection.