ObjectiveTo explore the feasibility and safety of modified semi-ex vivo small intestinal autotransplantation (IAT) in patients with distal cholangiocarcinoma (CC) involving mesenteric root. MethodThe clinicopathologic data of the patient with relapse after CC surgery admitted to Sichuan Provincial People’s Hospital on October 2022 were retrospectively analyzed. ResultsThe patient was a 40 years old male. The preoperative imaging showed that the superior mesenteric artery (SMA) and jejunal artery was surrounded by the tumor. The preoperative condition was good and the heart, lung, liver, and kidney functions were normal. The patient could tolerate surgery, then the modified semi-ex vivo IAT was performed. The patient recovered well after surgery and discharged on the 14th postoperative day. The postoperative pathological diagnosis result showed that it was CC. The patient was well and without recurrence or metastasis during following-up in the outpatient service for 5 months until April 2023. ConclusionsFrom the retrospective analysis of this case, it can be realized that the modified semi-ex vivo IAT for patients with tumor involving themesenteric root, it is safe and feasible. A treatment option can be provided for such patient.