Omeprazole is a proton pump inhibitor, through the regulation of gastric acid secretion, to achieve the efficacy of prevention and treatment of ulcers, the role and mechanism mainly include the following aspects: I. The role of inhibition of gastric acid secretion, omeprazole can make the basic gastric acid secretion of normal people and ulcer patients, as well as due to histamine, gastrin and other stimulation caused by gastric acid secretion are significantly inhibited, the inhibition is strong and lasting; II. Protective effect of gastric mucosa, omeprazole has obvious protective effect on gastric mucosa damage due to aspirin, ethanol, stress and other factors; iii. Anti-Helicobacter pylori effect, as H. pylori is proved to be one of the causes of ulcer disease, so it enhances the eradication rate of antibacterial drugs on H. pylori by anti-H. pylori.