1.Irrational diet: long-term consumption of moldy grain, moldy food, pickled vegetables, smoked and pickled fish and excessive salt intake can increase the risk of stomach cancer. These foods contain high concentration of nitrate, which can be easily absorbed by the body and converted into nitrite by bacterial reductase in the stomach, and then combined with amine into carcinogenic amine nitrite. Diet triggering gastric cancer is also one of the easiest factors to avoid. 2.Infection of Helicobacter pylori: The toxin secreted by it can cause lesions of gastric mucosa, so we must pay attention to our own health and avoid the factors that can induce gastric cancer. 3.Genetic factors: Genetic factors are one of the causes of gastric cancer. According to epidemiological survey, stomach cancer has the tendency of family gathering, so such people should pay special attention to the prevention of stomach cancer. 4. Precancerous lesions: i.e. systemic or local diseases and states prone to malignant changes, such as chronic atrophic gastritis, adenomatous gastric polyps, residual gastritis, etc.