Objective · To explore the value of applying CT/MRI image registration and fusion combined with 3D printing technique in pre-surgical planning of refractory pelvic tumors.  Methods · A retrospective analysis was performed on the cases with refractory pelvic tumors admitted between March 2014 and December 2016 in Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine. CT/MRI examinations were performed as a routine pre-surgical procedure, and the resulting images were subject to rapid registration and fusion with the Medraw software in order to accurately determine the tumor boundaries and to be used as references in designing and making patient-specific tumor models, prostheses, and implants by 3D printing technique.  Results · A total of 13 cases with refractory pelvic tumors were included in this study (8 cases of chondrosarcoma, 1 case of osteosarcoma with aneurysmal bone cyst, 1 case of dedifferentiated sarcoma, 1 case of fibrous connective tissue hyperplasia, 1 case of solitary fibrous tumor/hemangiopericytoma, and 1 case of metastatic squamous cell carcinoma) with an average age of (50.0±8.5) years. According to the Enneking classification，there were 2 cases in zone Ⅰ , 2 in zones Ⅰ + Ⅱ , 1 in zones Ⅱ + Ⅲ , 3 in zones Ⅰ + Ⅱ + Ⅲ , 1 in zones Ⅰ + Ⅱ + Ⅳ , 1 in zones Ⅰ+Ⅱ+Ⅲ+Ⅳ, 1 in zones Ⅰ+Ⅳ, 1 in zones Ⅱ+Ⅳ, and 1 in zone Ⅳ . The mean maximal tumor diameter was (15.15±4.81) cm without implicating the pelvic blood vessels. Results from intraoperative frozen section at resection boundaries and the installation of prosthesis showed that the actual surgical procedure was consistent with the surgical planning based on the reported image fusion technique.  Conclusion · CT/MRI image registration and fusion technique combined with 3D printing technique can accurately determine the resection boundary of pelvic tumors and assist in designing of individualized prosthesis model and surgical guide, which has a great value in pre-surgical planning and clinical treatment of refractory pelvic tumors.