The O2 stage of atrophic gastritis means that the atrophy of the gastric mucosa extends from the gastric sinus to the entire fundus of the stomach, and it is a type of atrophic gastritis with a relatively wide range of atrophy. Clinically, atrophic gastritis is generally categorized into six types according to the atrophic range of gastric mucosa, including C1, C2, C3, O1, O2 and O3. From the antrum to the lesser curvature of the stomach, if it fails to exceed the cardia, it is the closed type, i.e., C type. If it exceeds the cardia, it is the open type, i.e., O type. The limits of gastric mucosal atrophy range from the gastric sinus, gastric angle, and the lesser curvature of the gastric body to the cardia as type C1, type C2, and type C3, respectively. The limits of gastric mucosal atrophy range from the gastric sinus just past the cardia, throughout the gastric fundus, and extending to the gastric body as type O1, type O2, and type O3, respectively. Patients with type O2 atrophic gastritis need to take active drug treatment, including eradication of Helicobacter pylori if there is Helicobacter pylori infection, as well as acid-suppressing or antacid treatment, and the application of gastric mucosa-protecting drugs. If patients experience stomach discomfort, they should go to the hospital in time and under the guidance of the doctor for standardized treatment to avoid the progression of the disease.