Objective To study the changes of gastrin 17 (G17) and pepsinogen (PG) after gastric bypass surgery in gastric antrum resection, and the influences of different surgical methods on postoperative peptic ulcer. Methods Clinical data of 63 patients with gastric bypass surgery in our hospital from October 2013 to October 2015 were divided into resection of pyloric antrum group (n=33) and preserved pyloric antrum group (n=30). The values of G17, PGⅠ, PGⅡand PGⅠ/PGⅡwere detected by enzyme linked immunosorbent assay at 1 month, 6 months and 12 months after operation. The correlation between the different surgical methods and the incidence of peptic ulcer was analyzed between two groups. Results The G17 levels were significantly decreased in resection of pyloric antrum group 6 and 12 months after operation than those in preserved pyloric antrum group (P<0.05). Compared with preserved pyloric antrum group,PGⅠ and PGⅡ levels was significantly decreased 12 months after operation (P<0.05). There was no significant difference in the ratio PGⅠ/PGⅡat 1 month, 6 months and 12 months after operation between two groups (P>0.05). There was no significant difference in postoperative peptic ulcer between two groups (P>0.05). Conclusion Gastric bypass after resection of the pyloric antrum can reduce the postoperative secretion of G17, PGⅠ and PGⅡ, but which can not reduce the incidence of postoperative anastomotic ulcer.