With the improvement of people’s living standard, people’s awareness of health care is also gradually increasing. As we all know, the incidence of gastric cancer is high in China, and the current treatment effect is yet to be improved. Therefore, how to prevent the occurrence of stomach cancer is becoming more and more important. Medical research shows that some diseases are related to the occurrence of gastric cancer, such as chronic atrophic gastritis, chronic gastric ulcer, residual stomach, gastric polyps, etc. 1. Chronic atrophic gastritis is a common disease with incidence rate of 22% to 37%. Follow-up studies show that the incidence of gastric cancer in chronic atrophic gastritis is 7% to 13%. It is mainly a high-risk disease for gastric cancer in the elderly population, but it is also not uncommon in young people. Chronic atrophic gastritis has a long history and is often recurrent, with poor results of medical treatment. If gastroscopy reveals mucosal erosion, and if the mucosal biopsy is severe atypical hyperplasia, surgical treatment should be considered. With the improvement and formalization of medical treatment of gastric ulcer, most of the chronic gastric ulcers can be cured by medical treatment. It is now believed that chronic gastric ulcers have lost their significance for gastric cancer. Japanese scholars have shown that the malignancy rate of gastric ulcers observed in follow-up studies for 5 years is 0, and the malignancy rate of gastric ulcers observed for more than 9 years is 2.2%. It is important to note that regular medical treatment of gastric ulcers must be carried out. 3. The residual stomach refers to the remaining stomach tissue after partial gastrectomy due to stomach disease. The cancer rate of residual stomach is generally less than 2%. For the residual stomach after surgery for benign gastric diseases or gastric cancer, standardized review and follow-up should be carried out under the guidance of doctors, and the misconception of “stomach removed, no gastric cancer” must be corrected. 4.Gastric polyp is also a benign disease related to gastric cancer, which can be roughly divided into tumor and non-tumor polyp. Non-neoplastic polyps include inflammatory, hyperplastic, misshapen and ectopic polyps. Inflammatory, misshapen and ectopic polyps are generally not malignant, and the cancer rate of hyperplastic polyps is generally less than 2%, such as small polyps can be electrically removed endoscopically with little pain and trauma and fast recovery. If the polyp is growing fast, suspected of malignant change or not suitable for endoscopic electrodesection, part of the stomach can be removed surgically. The cancer rate of adenoma is higher, generally around 20%. If adenoma is found to be growing faster or with related uncomfortable symptoms, you should go to the hospital in time and have reasonable treatment under the guidance of doctors. Of course, the pathogenesis of gastric cancer is very complicated, and it is also necessary to pay attention to good dietary habits in daily life, such as paying attention to the freshness of food and increasing the consumption of fresh vegetables, fruits, milk and fish. Especially, the increased intake of onion and garlic has a protective effect on the occurrence of gastric cancer.