1.Where esophageal, gastric and duodenal diseases are suspected and the diagnosis is not confirmed by comprehensive examination (including X-ray examination). 2.Patients with retrosternal pain, burning sensation and difficulty in swallowing, suspected to have esophageal disease. 3.Peptic ulcer, which requires gastroscopy to follow up its healing and identify its benign and malignant nature. 4.Screening of gastric cancer and esophageal cancer, gastroscopy can improve the accuracy of diagnosis, detect early cases, and treat them. 5.Polyps and bulging lesions in upper gastrointestinal tract of stomach and esophagus need to be treated by gastroscopy and followed up in due course. 6.For bleeding cases in the upper gastrointestinal tract within 48 hours, emergency gastroscopy is advisable to determine the etiology and facilitate the adoption of timely and reasonable treatment plans. 7, Some chronic inflammatory diseases of the upper gastrointestinal tract, such as chronic atrophic gastritis with intestinal epithelial hyperplasia or atypical hyperplasia, may require repeated gastroscopy for treatment and follow-up. 8, cases after major gastrectomy require timely gastroscopy follow-up. 9, foreign bodies in the esophagus and stomach and other diseases that can be treated by gastroscopy.