Effective screening methods for gastric cancer are the key to early detection, early diagnosis and early treatment of gastric cancer. People with the following factors should be designated as high-risk groups for early or regular screening: (1) People over 40 years of age, especially men, who have recently developed dyspepsia or suddenly developed vomiting blood or black stools. (2) Those with proposed benign ulcer and lack of gastric acid; chronic atrophic gastritis, especially type A, with enterosis and atypical hyperplasia; (3) Gastroscopy should be performed immediately if the gastric ulcer is ineffective after two months of treatment and X-ray shows that the ulcer has increased in size instead; (4) Symptoms of chronic abdominal distension, heartburn, acid reflux, nausea and vomiting, early satiety, belching, burping, and progressive wasting (5) Symptoms of vomiting blood and black stool (6) History of gastric disease (7) Family history of gastrointestinal cancer (8) Frequent smoking, alcohol consumption, frequent consumption of moldy and pickled food (9) Gastroscopy should be done if gastric polyps larger than 2 cm are found on X-ray (10) Regular annual follow-up should be done more than 15 years after gastrectomy.