Objective To analyze the effect of inner diameter of pancreatic duct following pancreaticoduodenectomy on pancreatic fistula. Methods From January 1995 to December 2008, 256 patients underwent pancreaticoduodenectomy were divided into four groups based on the types of pancreaticojejunostomy: end-to-side “mucosa-to-mucosa” anastomosis group (n=115), end-to-end “mucosa-to-mucosa” anastomosis group (n=71), end-to-end invaginated pancreaticojejunostomy group (n=43) and pancreaticogastrostomy group (n=27). Alternatively, 238 patients were divided into two groups according to drainage ways: stenting tube for internal drainage group (n=132) and stenting tube for external drainage group (n=106). Furthermore, 233 cases were divided into three groups on the basis of inner diameter of pancreatic duct: ≤0.2 cm group (n=54), 0.2-0.4 cm group (n=93) and ≥0.4 cm group (n=76). Then, the incidence rate of pancreatic fistula of each group was compared. Results The incidence of pancreatic fistula was 8.20% (21/256). The incidence of pancreatic fistula for different types of pancreaticojejunostomy was as follow: end-to-side “mucosa-to-mucosa” anastomosis group (7.83%， 9/115), end-to-end “mucosa-to-mucosa” anastomosis group (7.04%, 5/71), end-to-end pancreaticogastrostomy invaginated group (13.95%, 6/43) and pancreaticogastrostomy group (3.70%, 1/27), in which there wasn’t significant difference in 4 groups （χ2=2.763，P=0.430）. There was no significant difference of the incidence of pancreatic fistula between stenting tube for internal drainage group (9.10%, 12/132) and stenting tube for external drainage group (8.49%, 9/106), χ2=0.126, P=0.722. The incidence of pancreatic fistula in ≥0.4 cm group, 0.2-0.4 cm group and ≤0.2 cm group was respectively 0, 15.05% (14/93) and 11.11%(6/54), and the difference was significant (χ2=12.009, P=0.002). No correlation was found between the incidence of pancreatic fistula of different inner diameter of pancreatic duct and the types of pancreaticojejunostomy (χ2=1.878， P=0.598). Conclusion The inner diameter of pancreatic duct is an important factor for postoperative pancreatic fistula. No relationship is found between the types of pancreaticojejunostomy and pancreatic fistula in this study.