Malignant tumors originating in the talus are rare and present significant challenges in reconstruction. Traditional treatments, such as below-knee amputation or tbiocalcaneal fusion, often result in significant loss of ankle function. After tumor resection, reconstruction of the talus and calcaneus is necessary to preserve ankle function. However, the intricate anatomical structure and unique location of the talus and calcaneus present significant challenges for prosthetic reconstruction.Here, we present the case of an 11-year-old adolescent patient diagnosed with Ewing's sarcoma of the talus, accompanied by suspected involvement of the calcaneus. Following a comprehensive evaluation, a 3D-printed talus-calcaneus prosthesis, which is composed of a ultrahigh-molecular weight polyethylene (UHMWPE) part and a titanium alloy part, was designed for talus and calcaneus reconstruction. In addition, a porous structure was designed to promote the integration of bone-prosthesis interface. The lesion was completely resected and the prosthesis was precisely installed. After 12 months follow-up, patients demonstrated favorable function results with the Musculoskeletal Tumor Society (MSTS) score was 27/30, and the American Orthopedic Foot and Ankle Society (AOFAS) score was 92/100. The range of motion for dorsiflexion, plantarflexion, inversion, and eversion of the right ankle joint was measured as 10° and 35°, 15°, and 10°, respectively. The postoperative radiograph showed a good position of the prosthesis. No narrowed joint space was observed. Tomosynthesis shimadzu metal artifact reduction technology (T-SMART) revealed that integration between bone and prosthesis was good.In this case, we present a case of 3D-printed talus-calcaneal prosthesis reconstructing talus and calcaneus. Favorable postoperative function outcome and good integration of the interface were observed. Therefore, this case provides an alternative therapeutic option for the treatment invasive talus tumor accompanied by suspicious contamination of the calcaneus. Nevertheless, a larger cohort study and with longer follow-up is needed to evaluate the effectiveness and potential complications of this novel prosthesis.© 2024 The Author(s). Orthopaedic Surgery published by Tianjin Hospital and John Wiley & Sons Australia, Ltd.