BACKGROUND: Surgery is usually recommended to treat retroperitoneal tumors. However, complete surgical resections often remain challenging. OBJECTIVE: To assess the assistant role of three-dimensional (3D) imaging and printing model in retroperitoneal tumor resection, as well as compare the difference between 3D printing and computed tomography (CT) in preoperative planning and confidence building. METHODS: We admitted a patient with retroperitoneal mass (13.0×6.4×14.8cm) adjacent to important abdominal blood vessels whose surgery was thought to be difficult. 3D printing and CT was arranged. A novel questionnaire and scoring system consisting of surgery difficulty and safety were designed to compare doctors understanding and confidence for surgery based on 3D printing and CT. Twenty-four doctors completed the scoring table based on CT and then 3D imaging, respectively. Paired t-test was applied for statistics analysis. RESULTS: Preoperative evaluation based on 3D printing indicated that the tumor could be removed completely. The operation lasted 120 minutes to successfully remove the tumor and the estimated blood loss was less than 100ml. Scores based on 3D printing is significantly higher than CT in difficulty and safety of surgery (p<0.001). Interestingly, the junior doctors seem to benefit more from 3D printing than the senior doctors. CONCLUSIONS: 3D imaging and printing model provides greater help for preoperative planning and confidence building than using CT in resection of retroperitoneal tumor, especially for the junior doctors. © 2020 - IOS Press and the authors. All rights reserved.