The diagnosis of chronic gastritis depends mainly on endoscopy and gastric mucosal biopsy, with the latter in particular being of greater diagnostic value. In view of the fact that most patients with chronic gastritis do not have any symptoms, and even if they do have symptoms, they lack specificity and lack specific signs, so it is difficult to make a correct diagnosis of chronic gastritis based on symptoms and signs. The diagnosis of chronic gastritis depends mainly on endoscopy and gastric mucosal biopsy, especially the latter being of greater diagnostic value. The diagnosis of chronic gastritis should seek to clarify the etiology, and routine detection of Hp is recommended. Hp infection is the main cause of chronic gastritis, and is recommended as a routine test for the etiological diagnosis of chronic gastritis. In chronic gastritis, serum gastrin G17 levels are significantly elevated in those with gastric body atrophy, and pepsinogen I or pepsinogen I/II ratio is reduced; in those with gastric sinus atrophy, the former is reduced and the latter is normal; in those with total gastric atrophy, both are reduced. Therefore, the detection of serum gastrin G17 and pepsinogen I and II can help determine the presence of gastric mucosal atrophy and the site of atrophy. Atrophic gastritis can be caused by Hp infection or autoimmunity, and testing of serum gastrin, vitamin B12, and anti-mural cell antibodies and anti-internal factor antibodies is recommended in cases where autoimmunity is suspected.