1, the legacy of acute gastritis: after acute gastritis, gastric mucosal lesions persistent or recurrent, can form chronic: gastritis. 2, irritating food and drugs: long-term use of diet and drugs that strongly stimulate the gastric mucosa, such as strong tea, strong alcohol, spicy or salicylate drugs, or inadequate chewing when eating, rough food repeatedly damage the gastric mucosa, or excessive smoking, tobacco acid directly on the gastric mucosa caused. 3, the reflux of duodenal fluid: research found that patients with chronic gastritis due to dysfunction of the pyloric sphincter muscle, often causing bile reflux, may be an important causative factor. Phospholipids in pancreatic juice, together with bile and pancreatic digestive enzymes, can dissolve mucus and destroy the gastric mucosal barrier, prompting H+ and pepsin to anti-diffuse into the mucosa, further causing damage. The resulting chronic gastritis is mainly in the gastric sinus. 4, immune factors: changes in immune function in the pathogenesis of chronic gastritis has generally been paid attention to, atrophic gastritis, especially gastric body gastritis patients can be found in the blood, gastric juice or within the atrophic mucosa mural cell antibodies; gastric atrophy with pernicious anemia patients found in the blood of endogenous factor antibodies, indicating that autoimmune reactions may be a relevant cause of some chronic gastritis. 5, infection factors: research found that patients with chronic gastritis in the gastric sinus mucus layer near the epithelial cell surface there is a large number of Helicobacter pylori, the positive rate of up to 50% to 80%, this bacteria is not seen in the normal gastric mucosa. Where the bacterium settled are seen gastric mucosal inflammatory cell infiltration, and the degree of inflammation is related to the number of bacteria.