Abstract: OBJECTIVE To investigate the effect of gastrin 17 and pepsinogen on primary gastric cancer and its effect on infection. METHODS A total of 248 patients with gastric cancer admitted to our hospital from Jan. 2013 to Dec. 2016 were selected as the subjects. Patients were divided into 112 cases of early gastric cancer group (T1-2) and 136 cases of advanced gastric cancer group (T3-4) according to the different stages of gastric cancer. A total of 130 healthy persons with physical examination were selected control group at the same time. The preoperative serum gastrin-17 content and pepsinogen content between physical examination and gastric cancer patients were compared, and the postoperative serum gastrin-17 content and pepsinogen content between infected patients and non-infected patients were compared. The specificity, sensitivity and accuracy of gastrin-17 content and pepsinogen to primary gastric cancer were determined. The pathogens in infected patients were statistically analyzed. RESULTS The levels of gastrin-17, pepsinogen Ⅰ and Ⅱ in early gastric cancer group were (12.41±5.73) pmol/L, (60.34±8.14) ng/ml, and (14.28±1.93) ng/ml, respectively, which were significantly lower than those in advanced gastric cancer group of (19.73±8.84) mol/L, (87.53±12.42) ng/ml, and (28.76±5.41) ng/ml , respectively (P<0.05). The best critical values of gastrin-17, pepsinogen Ⅰ and Ⅱ for the diagnosis of gastric cancer were 9.71 pmol/L,67.96 ng/ml,and 13.52 ng/ml, the sensitivities were 80.83%,74.41%,and 88.78%,the specificities were 63.9%,55.24%,and 84.63%, and the accuracies were 59.07%,63.22%,and 59.58%, respectively. The contents of gastrin-17, pepsinogen I and II in the control group and non-infected patients were significantly lower than those in the infected patients (P＜0.05). The best critical values of gastrin-17, pepsinogen Ⅰ and Ⅱ for the diagnosis of postoperative infection of gastric cancer were 18.86 pmol/L,81.73ng/ml,and 22.6 1ng/ml, the sensitivities were 84.22%,85.75%, and 82.11%, the specificities were 84.29%,87.74%,and 71.90%, and the accuracies were 69.77%,72.81%,and 67.44%, respectively. Totally 21 strains of pathogenic bacteria were isolated from 18 cases of infected patients, including 13 strains of gram-negative bacteria, 7 strains of gram-positive bacteria and 1 strain of fungus. CONCLUSION Gastrin-17 and pepsinogen have important diagnostic values in primary gastric cancer and postoperative infection of gastric cancer, and we should pay attention to it in clinical practice.