Objective To introduce the application of SimPlant software to match contour of iliac crest and mandibular defect before operation in order to guide harvesting iliac osteo-myocutaneous flap and reconstructing mandible.Methods Before operation,SimPlant software was used to simulate segmental mandibulectomy and auto-match contour of iliac crest and mandibular defect so that harvesting and shaping iliac osteo -myocutaneous flap could be calculated.Segmental mandibulectomy and mandibular reconstruction with iliac osteo-myocutaneous flap were performed according to preoperative design.Results The facial appearances of the patients according to preoperative design were symmetry.Post-operative panoramic radiograph and three-dimensional CT scan revealed that the contour of mandible reconstructed with iliac crest flap was ideal and the condyles were located within the glenoid fossa.Conclusion Application of SimPlant software to auto-match donor and recipient site can simplify the operation of mandibular reconstruction with iliac osteo-myocutaneous flap,reduce the operative damage,increase the accurate result,and create good condition for functional mandibular reconstruction.