Objective　To explore the surgical strategy of internal fixations for supracondylar fractures of femur using Mimics18.0 digital software combining with three-dimensional (3D) printing technique.　Methods　Thin slice CT scan data of 10 cases of complicated supracondylar fractures of femur and the data of all the internal fixations were imported into Mimics18.0 software to reconstruct 3D models, where virtualfracturesreductions were performed,standard parts library of internal fixations were established, and the most appropriate plates and screws were chosen. A 1:1 3D femur model was printed to simulate the surgery based on the digital design. Comparisons were made on the plate positions, screw passage lengths and screw directions to determine the final internal fixations. After that, the fracture reductions and internal fixations were performed in the reality surgery. An evaluation scale was handed out to patients and their relatives to investigate their altitudes to surgery simulations and 3D printing models.　Results　3D printing is of great use in reductions of supracondylar fractures. In simulated surgery of the typical case, 1 reconstruction plates and 8 screws were implanted in the 3D printing model, and the plate positions and the screw directions were in high accordance with those measured in Mimics 18.0 software. The comparisons between simulated surgery and digital design on screw length had nosignificantdifference(P>0.05).The effectiveness of reality surgery was also consistent with the simulated surgery. Patients also had high satisfactions with the surgical strategy of using 3D model before operation. Conclusion　Three-dimensional (3D) printing and digital design technique are of great value in individualized surgery and precise treatment, and can result in good physician-patient communication effects.