Chronic atrophic gastritis is a chronic gastritis characterized by atrophy of the epithelium and glands of the gastric mucosa, reduction in number, thinning of the gastric mucosa, thickening of the mucosal base, or with pyloric glandular hyperplasia and intestinal glandular hyperplasia, or atypical hyperplasia as a chronic digestive disease. It is often characterized by vague pain in the upper abdomen, fullness, belching, loss of appetite, or wasting, anemia, etc. The signs are not obvious, and sometimes there is light pressure pain in the upper abdomen. The main pathogenic factors include: H. pylori infection: when H. pylori enters the stomach through the mouth, part of it will be killed by gastric acid, and part of it will attach to the mucus layer of the gastric sinus, settling in the mucus layer on the surface of the mucosal epithelial cells of the gastric sinus, and generally does not invade the gastric glands and the lamina propria. The urease produced by H. pylori can decompose urea, and the ammonia produced can neutralize the gastric acid that re-infiltrates into the mucus, forming a local microenvironment conducive to the settlement and reproduction of H. pylori, making the infection chronic. H. pylori causes cellular damage by virtue of its production of ammonia and vacuolar toxins; promotes the release of inflammatory mediators from epithelial cells; Duodenal-gastric reflux: caused by chronic inflammation of the stomach and intestines, digestive malabsorption and abnormal dynamics. Long-term reflux can lead to chronic inflammation of the gastric mucosa. Bad living and eating habits: smoking, alcohol consumption, food irritation, drugs that damage the gastric mucosa, etc. Autoimmunity: Gastric body gland wall cells secrete a mucin, called endoglin, in addition to hydrochloric acid. It binds to vitamin B12 (exo-factor) in food to form a complex so that it is not digested by enzymes and reaches the ileum, where vitamin B12 is absorbed. When autoantibodies against mural cells or endoglin appear in the body, the total number of mural cells as target cells decreases, gastric acid secretion decreases, and endoglin fails to function properly, resulting in malabsorption of vitamin B12 and megaloblastic anemia, called pernicious anemia. Age factor and gastric mucosal nutrient factor deficiency: distortion of small mucosal vessels, glassy degeneration of small arterial walls and luminal narrowing are common in the gastric mucosa of the elderly. This gastric local vascular factors can make mucosal malnutrition, food mono, nutritional deficiency can be gastric mucosa repair and regeneration function is reduced, inflammation chronicity, epithelial proliferation abnormal and gastric gland atrophy. In addition, dietary habits, physical factors, genetic factors and other factors are also one of the causes of the disease. These are the causes of atrophic gastritis, therefore, it is necessary to actively prevent the disease before it occurs and try to avoid its occurrence.