Stomach cancer is one of the common malignant tumors that endanger people’s life and health. According to the survey data on the causes of malignant tumor death in China in the early 1990s, stomach cancer ranks third among the causes of malignant tumor death in urban areas and first in rural areas. Since the early symptoms of gastric cancer are easily confused with many benign diseases of stomach or liver and biliary diseases, it is easy to be overlooked and misdiagnosed or missed, and many patients are already in the middle or late stage when they are diagnosed. According to some data, early gastric cancer only accounts for about 10% of diagnosed cases in China, and about 60% of diagnosed gastric cancer cases can be radically resected, and the 5-year survival rate after surgery is about 50%, and nearly 50% of patients cannot be cured finally. Therefore, prevention and early detection of gastric cancer are especially important. Although the causes of gastric cancer are not fully understood, some factors closely related to the development of gastric cancer have been gradually elucidated. Among them, dietary factors are most closely related to the development of gastric cancer. It has been identified that more than 200 kinds of nitroso compounds can cause cancer in animals, and these carcinogens can exist in certain foods and enter the human body through diet to induce gastric cancer; many precursors of nitroso compounds, such as secondary amines and nitrites, exist more widely in nature and are transformed into nitroso compounds and cause cancer after entering the human body under the effect of certain internal environmental factors. Other carcinogens of gastric cancer include polycyclic aromatic hydrocarbons, aflatoxins, etc. Therefore, the incidence of gastric cancer can be reduced and the purpose of gastric cancer prevention can be achieved by controlling the entry of food and drinking water high in the above carcinogens into the human body or changing the internal environment of the human body to reduce the conversion of carcinogenic precursors into carcinogens. At present, it is known that salted meat, salted fish, salted vegetables, smoked, fried and baked meat, sausage, ham, canned meat and other meat products, fermented shrimp paste or fish sauce, etc. all contain more of the above carcinogens, so we should not eat or eat less of such foods. Do not eat moldy food or food, and advocate a low-salt diet (the World Health Organization recommends that each person’s daily salt intake should be below 6 grams); eat more fresh vegetables (such as eggplant, cabbage, potatoes, cabbage, garlic, onion, leek, onion and garlic seedlings, etc.) and fruits rich in vitamin C, E, beta-carotene and trace elements of selenium, and increase fresh meat, fish, eggs, milk and soybean products; popularize the use of refrigerators to prevent moldy food. The use of refrigerators is popular to prevent mold and mildew of food. Eating on time, not overeating, avoiding hard, coarse and hot foods, smoking less or not smoking, and drinking less strong alcohol also help to prevent stomach cancer. In addition, H. pylori is also closely related to the occurrence of gastric cancer, and long-term infection with H. pylori will increase the incidence of gastric cancer, so eradication treatment of H. pylori is one of the important measures to prevent gastric cancer. The occurrence of gastric cancer often goes through a long process, therefore, the prevention of gastric cancer should start from young adults. Follow-up, regular fiberoptic gastroscopy review and treatment of precancerous state (such as chronic atrophic gastritis, gastric ulcer, gastric polyp, postoperative residual stomach of benign gastric diseases) and precancerous lesions (heterogeneous hyperplasia of gastric mucosa epithelium, intestinal epithelial hyperplasia of gastric mucosa) are of great significance for the prevention of gastric cancer.