Objective To explore the diagnostic value of serum pepsinogen Ⅰ(PG-Ⅰ), Ⅱ(PG-Ⅱ) and gastrin 17(G-17) in the diagnosis of chronic atrophic gastritis(CAG). Methods We selected 112 patients with chronic atrophic gastritis diagnosed in our hospital from July 2019 to July 2020 as the observation group, and selected 112 patients with chronic non-atrophic gastritis who were examined in our hospital during the same period as the control group. The levels of PG-Ⅰ, PG-Ⅱ, PG-Ⅰ/PG-Ⅱ(PGR) and G-17 in the serum of the two groups of patients were detected by fluorescence immunoassay. The diagnostic efficiency and the specificity and sensitivity of the diagnosis of CAG were analyzed by ROC curve. The three indicators and indicators combined to diagnose the specificity and sensitivity of the above diseases are analyzed by ROC curve. Results Compared with the control group, the observation group patients' serum PG-Ⅰ, PGR and G-17 levels were significantly reduced, and the difference was significant(P＜0.05). In terms of PG-Ⅱ levels, there was no significant difference between the two groups(P＞0.05). In the observation group, gastric body atrophy was compared with multifocal atrophy of whole stomach and antral atrophy, the gastric atrophy group PG-Ⅰ, PG-Ⅱ and PGR levels were significantly reduced, and the G-17 level was significantly increased(P＜0.05); The ROC curve was used to draw the area under the CAG curve for PG-Ⅰ, PG-Ⅱ, G-17 and the combined index, which were 0.895, 0.873, 0.881, and 0.903 respectively. Compared with the control group, the positive rate of Hp in the observation group increased significantly, the difference has significant(P＜0.05). The analysis of the observation group showed that the Hp-positive patients and the Hp-negative patients PG-Ⅰ, PG-Ⅱ, G-17 There was no significant difference in level comparison(P＞0.05). Conclusion Serum PG-Ⅰ, PGR and G-17 levels have a certain relationship with the occurrence and development of CAG. The clinical combined detection of serum PG-Ⅰ, PGR and G-17 levels is of high value for the early diagnosis of the disease, Which is helpful for early treatment of disease.