Stomach cancer is one of the most common malignant tumors in China, and the mortality rate remains high, with one out of every four deaths due to malignant tumors. Therefore, stomach cancer is a disease that seriously endangers the life and health of our people. The treatment effect of gastric cancer is closely related to the stage of the disease. Most early gastric cancers can be cured by early treatment, while the five-year survival rate of patients with advanced gastric cancer is less than 5%. Definition of high-risk groups: patients with precancerous gastric lesions (atrophic gastritis, ulcer disease, post-operative residual stomach, etc.); those with H. pylori infection; those with poor dietary habits; long-term alcoholics and smokers; those with mental stimulation and sulking; those with family history of gastric cancer or other gastrointestinal cancers; those with long-term exposure to sulfuric acid dust, lead, asbestos, herbicides and metal industries. Screening program: Test serum pepsinogen (PG) level, if it is greater than normal, gastroscopy should be performed (normal value: PGⅠ ≤ 70ug/L, PGⅠ/Ⅱ ≤ 7) Gastroscopy + indigo carmine staining + indicative biopsy