Objective To investigate the effect of common iliac vein allograft replacing the portal vein-superior mesenteric vein transition area invaded by pancreatic cancer. Methods The clinical data of a patient with pancreatic cancer admitted to the Beijing Tsinghua Changgung Hospital in December 2021 who underwent pancreaticoduodenectomy combined with common iliac vein allograft replacing the junction of portal vein, superior mesenteric vein and splenic vein were analyzed retrospectively. The patient was a 77-year-old man who complained of “epigastric pain for 1 month and pancreatic mass was found for 1 week”. After admission, the patient was diagnosed with pancreatic cancer through inspection, and then the surgery was required. Preoperative examination and intraoperative exploration confirmed that the junction of portal vein, superior mesenteric vein, and spleen vein was invaded by tumor. In addition, the length of the invaded vessels measured by preoperative 3D reconstruction image was 5.5 cm, and the distance between the broken end of portal vein and the broken end of superior mesenteric vein measured was 4.5 cm during the operation. After tumor and vessels were resected, vascular anastomosis could not be performed directly. After accurate evaluation, pancreaticoduodenectomy combined with common iliac vein allograft replacing the junction of portal vein, superior mesenteric vein and splenic vein was performed. The operative time was 11 h, and the intraoperative blood loss was 400 mL. After the operation, the routine treatment was performed in ICU and was transferred to the general ward on the 7th day. Postoperative laboratory tests were performed to monitor liver function changes routinely, and imaging examination were was performed to monitor portal venous system blood flow. Results Postoperative complications such as biliary fistula, pancreatic fistula, hemorrhage, infection and thrombosis were not occurred. Postoperative pathological diagnosis: pancreatic ductal adenocarcinoma, medium-low differentiation. Enhanced CT reexamination on the 2nd and 13th day after the operation showed that the blood flow at the junction of portal vein, superior mesenteric vein and splenic vein of the common iliac vein allograft was unobstructed, and there was no stenosis or thrombosis at each anastomosis. Conclusions The application of common iliac vein allograft replacing the portal vein-superior mesenteric vein transition area invaded by pancreatic cancer is safe and feasible. The short-term efficacy is satisfactory, and long-term prognosis remains to be further observed.