Esomeprazole is a proton pump inhibitor that mainly has the effect of inhibiting gastric acid as a specific inhibitor of the proton pump in the cells of the stomach lining. It belongs to the isomer of omeprazole, which can reduce the secretion of gastric acid by specific proton pump inhibition. Esomeprazole is a weakly alkaline drug that concentrates in the gastric lining cells to inhibit the proton pump in this area, and has an inhibitory effect on both basal gastric acid secretion and stimulated gastric acid secretion. It can be used clinically for patients with gastroduodenal ulcer, gastroduodenal bleeding, and reflux esophagitis. Besides, it can also be used in combination with other drugs for anti-Helicobacter pylori treatment. In conclusion, Esomeprazole is a proton pump inhibitor, which mainly has the effect of inhibiting gastric acid.