Objective To study the law of shape changes of mandiblular distraction osteogenesis in the patient with hemifacial microsomia(HFM) and compare the results with the real effect on the patient by establishing the models of mandibular and masticatory muscles, and to put forward some good suggestions on procedures of treating patients diagnosed as HFM and related cases. Methods Based on the original data of the patient with HFM, combined with the MIMICS software (medical image control system software), the model of the patient’s mandibular and masticatory muscles was constructed by applying the technique of three dimensional (3D) reconstruction, and then put the entity structure into the ANSYS software to simulate the effect of the surgery. Results The established preoperative and postoperative finite element analytic model could present the characteristics such as digitalization and individuation. Conclusions Compared with the effects of the real surgery for the same patient, the result of numerical simulation showed to be good matching and could provide personalized guidance for different patients before their operation.