Most patients with biliary tract cancer are diagnosed at advanced stage and lose the opportunity for radical surgery resulting in dismal prognosis. In recent years, with advances in therapeutic approaches, conversion therapy has gradually been implemented in some cases of initially unresectable biliary tract cancer, enabling a subset of patients to achieve opportunities for radical surgery. To further standardize conversion therapy of biliary tract cancer and improve the overall efficacy, the Branch of Biliary Surgery, Chinese Society of Surgery, Chinese Medical Association and Working Group of Biliary Surgeons, Chinese College of Surgeons, Chinese Medical Doctor Association, based on the latest evidence-based medical evidence and specific practices in the treatment of biliary tract cancer in China, organized discussion among experts in the field. Following the discussion, the "Expert consensus on conversion therapy of biliary tract cancer (2025)" was developed. This consensus aims to address key issues in the field of biliary tract cancer conversion therapy, standardize diagnostic and therapeutic procedures and protocols，and lay the foundation for further advancing research and practice in this area.