Abstract: Objective To investigate the variation of pepsinogen (PG)Ⅰ,pepsinogen (PG)Ⅱ and ratio of PGⅠ/PGⅡ(PGR) in serum of gastric cancer patients and its relation to Helicobacter pylori infection,and discuss its role in clinicopathologic study of this disease. Methods A total of 250 gastric cancer patients were selected as study group,and 120 healthy people were selected as control group in our hospital from January,2015 to June,2016.The serum levels of PGⅠ,PGⅡ,PGR were tested by chemical luminescence method and the serum level of Helicobacter pylori (Hp) IgG antibody was tested by latex immunoturbidimetry method to detect Hp infection.The results were compared between the two groups,the values of PGⅠ,PGⅡ,PGR to the diagnosis of gastric cancer were evaluated by ROC curve and the levels of PGⅠ,PGⅡ and PGR of different gender and age were compared both in study group and control group,and the relation between the levels of PGⅠ,PGⅡ,PGR and clinicopathologic features of the disease was analyzed. Results The levels of PGⅡ and positive rate of Hp in gastric cancer group were significantly higher than those in control group,while PGR in gastric cancer group was significantly lower (P<0.05).The area under ROC curve of PGR was 0.803,which was higher diagnostic value of gastric cancer than PGI or PGII.The levels of PGⅠ,PGⅡ in male or ≥ 60 years were significantly higher than female or <60 years in control group,and the level of PGI in advanced cancer was significantly lower than those in early cancer (P<0.05),and the level of PGR was correlated with Hp infection status. Conclusion The serum levels of PGⅠ,PGⅡ and PGR may be valuable to the diagnosis of gastric cancer,and PGⅠ may be useful to the TNM classification of gastric cancer.