The prognosis of hilar bile duct cancer has been improved by extensive curative resection, but massive hepatectomy can result in surgical and medical complications in high-risk patients. We report a case of type IIIb hilar bile duct cancer undergone S4a S5 with caudate lobe (S1) resection as a parenchyma-preserving hepatectomy. The operation was a modified type of Taj Mahal liver resection omitting parencymal transection between S4b and S8. Such an extent of hepatectomy combined with bile duct resection made 3 right and 3 left intrahepatic segmental duct openings, which were reconstructed as a whole at each side of transection plane after ductoplasty. The patient recovered uneventfully. Although surgical technique for S4a+S5+S1 must be more complex comparing with other anatomical hepatectomy, but it could be accepted as a safe curative resection for some selected patients with advanced hilar bile duct cancer, by which favorable recovery of the liver function may lead to prevention of postoperative complications. Comprehension to the anatomy of the intrahepatic ducts is a prerequisite for S4a+S5+S1 resection, thus we discussed it in detail.