Chronic atrophic gastritis in the active phase means that the patient has atrophic gastritis and is in the progressive phase of the disease. This means that the patient with chronic gastritis has atrophic changes in the gastric mucosa and chronic inflammatory cell infiltration, mainly lymphocytes and plasma cells, can be seen in the gastric mucosal layer. In fact, chronic atrophic gastritis is also a kind of chronic gastritis, except that it has undergone atrophic changes in the gastric mucosa, and when it is in the active stage, patients will show clinical symptoms such as abdominal pain, bloating, nausea, vomiting, acid reflux, and indigestion. The treatment of patients with atrophic gastritis is mainly based on gastric mucosal protective agents. When patients have abdominal pain, they can also be treated with drugs that inhibit gastric acid secretion, such as omeprazole or lansoprazole, as appropriate. However, for patients with atrophic gastritis, it is recommended that they must be closely followed up, about once every three months to six months, with electronic gastroscopy plus pathological examination to understand the progress of the atrophic lesions of the gastric mucosa, and if necessary, prophylactic surgery may be required.