The etiology of gastric cancer is complex, and there are various factors, such as heredity, environment, dietary habits, etc. The exact pathogenesis is still unclear, but there are two factors that have been clearly defined and can be controlled, one is Helicobacter pylori, and the other is nitrite. Therefore, by abandoning the already clear high-risk habits and precancerous lesions, taking targeted preventive measures, adopting the approach of early diagnosis, early prevention and early treatment, targeting secondary prevention, and treating gastric polyps and other diseases at the stage of early cancer, and controlling the continued development of the disease, we should be able to reduce the incidence and mortality of middle- and late-stage gastric cancer, and improve the 5-year survival rate of gastric cancer. It is crucial to do a good job in secondary prevention of gastric cancer. Primary prevention: i.e. etiological prevention, trying to control and treat known and suspected cancer-causing factors, removing the causes that may lead to gastric cancer, paying attention to dietary hygiene, avoiding cold, spicy and stimulating foods and barbecue foods, changing long-term bad habits: alcoholism, smoking, staying up late, anxiety, etc., refusing high salt, spicy and stimulating foods, processed meat foods, and refusing tobacco and alcohol; and promoting the use of public chopsticks to avoid the transmission of Helicobacter pylori bacteria. 2, do not eat pickled or barbecue smoked food, nitrite is mainly found in pickled food, high salt food, overnight vegetables, eat less of these things can be; 3, reduce the salt intake of food, salt control. 4, eat more fresh fruits and vegetables, dairy products, 5, increase the intake of fish, meat, increase protein content. Eradicate Helicobacter pylori, which is the main cause of gastric cancer in China. About 75% of gastric cancers are caused by Hp infection, and about 90% of non-cardia gastric cancers are closely related to Hp infection. For gastric ulcers or gastric polyps larger than 2cm that are ineffective in long-term treatment, endoscopic or surgical treatment should be carried out in time, and patients with chronic atrophic gastritis should be actively and regularly rechecked for gastroscopy. Secondary prevention: This is what we often call “three early” prevention, i.e. early detection, early diagnosis and early treatment. Before gastric cancer occurs, but precancerous diseases or precancerous lesions have already occurred, it should be detected and diagnosed in advance, so as to improve the survival rate and cure rate. (1) Carry out census and early cancer screening for high-risk groups in areas with high incidence of gastric cancer; (2) establish specialized outpatient clinics for gastric diseases, so as to achieve specialization and professional diagnosis and treatment, and to avoid leakage of diagnosis for high-risk groups and early cancer. (3) To do a good job of follow-up for high-risk susceptible people. For the age of 40 years old or older, patients with Helicobacter pylori infection, chronic atrophic gastritis, gastric polyps, gastric ulcers, gastric remnants, moderate to severe atypical hyperplasia, gastric ulcers, adenomatous polyps, verrucous gastritis, hypertrophic gastritis, family history of gastric cancer, and gastric remnants after surgery, patients should be informed to have regular and active review of the gastroscope and outpatient follow-ups. Eradication of Helicobacter pylori is the most important preventive means to prevent gastric cancer; testing and eradication treatment are recommended for adults with or without symptoms.