Objective: To find a new treatment to reconstruct the defects of mandible. Methods: 14 patients with mandibular defects were reconstructed by fibula free flaps after ostectomy immediately. Results: All flaps were survival with the success rate of 100%. The function and contour of the mandible were excellent. Facial contour in all patients was graded to be very good. X-ray films were taken to observe bone flap healing 3 months after surgery. And the aesthetic assessments in all patients were good or fair. no ankle unstability were reported. Conclusion: Fibula free flap has a good blood supply and high density of cortical bone. There is enough bone available. Vascularized free fibula flap takes its distinct advantages to other autogeneous free bone flaps and is confirmed to be one of the optimal methods for mandible reconstruction by our study.