Abstract: Ameloblastic fibro-odontosarcoma (AFOS) now designated as odontogenic sarcoma is an extremely rare odontogenic tumor, which histologically presents as a biphasic neoplasm with a malignant mesenchymal component plus ameloblastic epithelium. Here we report a 27-year-old Chinese female with the complaint of a painful swelling for half a month in the right mandible. A segmental mandibulectomy, with an immediate mandibular reconstruction using a free vascularized osteocutaneous fibular flap was performed using surgical guide models. Histological analysis revealed a primary odontogenic sarcoma. The postoperative period was uneventful, and no clinical indication of recurrence or metastasis was observed during the 3-year follow-up. No adjuvant therapy was proposed. This is the first odontogenic sarcoma case reported in China after the new World Health Organization classification of odontogenic lesions.