Stomach cancer is one of the common diseases that endanger human health, and its incidence is mostly in middle age and above, with the peak at the age of 40-50, and the incidence rate of men is two times more than that of women. There are many reasons for the development of stomach cancer, but diet has the closest relationship with stomach cancer. Stomach is the part of digestive tract where food stays for the longest time. Therefore, the stomach is exposed to harmful substances in food for a long time, and the incidence of stomach cancer accounts for 40% to 50% of the malignant tumors of digestive tract. Food is the essential nutrient for human body. It enters the stomach through the mouth and is digested, absorbed and metabolized in the body. The food we consume, some of which have cancer prevention effects, while others can cause or promote cancer. Such as salted fish, kimchi, bacon, pickles, moldy peanuts, beans, etc. These foods contain a large amount of nitrite and 3-4 benzo(a)pyrene and other chemicals, which are ingested and become nitrosamines with strong carcinogenic effect under the action of gastric acid, and scientific experiments have proved that nitrosamines are closely related to the occurrence of gastric cancer. The normal gastric mucosa has about 1mm thick mucosal layer, which is medically called “mucosal barrier”, which can prevent the invasion of external bacteria, viruses and carcinogenic substances and prevent the self-digestion of gastric acid. Some people have irregular diet, hungry for one meal, full for another, overeating and drinking strong alcohol, which cause chronic stimulation to the gastric mucosa, resulting in congestion, edema and erosion, and bacteria, viruses and carcinogenic substances will take advantage of the opportunity to enter and cause gastric mucosa cancer. The occurrence of gastric cancer is a chronic evolutionary process, which is not only related to the amount of carcinogenic substances ingested. It is also related to the physical condition of a person. In other words, it is not impossible to eat kimchi and salted fish occasionally, but as one of the cancer prevention measures, it is better to avoid eating such substances as much as possible. Many foods have cancer prevention and anti-cancer effects, such as fish, dairy products, eggs, fresh vegetables, fruits, carrots, tomatoes, mushrooms, shiitake mushrooms, etc. In order to prevent stomach cancer, we advocate good eating habits, reasonable regulation of diet, eating more foods with anti-cancer effects, avoiding or reducing cancer-causing foods, avoiding smoking and alcohol, and actively treating gastritis and other diseases.