Abstract: Objective: To analyze biomechanics of impact injury, in the condition of the simulate impact on mandible rejoins. Methods: A Finite Element Model of human mandible is developed from CT scan images by the technologies of three-dimensional reconstruction, image processing and meshing. The mandible model is connected to one modified head model of HYBRIDⅢ dummy with joint according to the anatomic structure and mechanical characteristics of the temporomandibular joint. Results: A finite element model of the human head with the true anatomic structure mandible has been developed. This model has been validated with the cadaver test results. The higher stress was showed in the condyle rejoins and coracoid in the model when mandible was in impact simulation. Conclusions: This model can be used to research the mechanism of craniofacial blunt-impact injury and assess the injury severity. The model of HYBRIDⅢ dummy with the human mandible was helpful for the boundary design of mandibular model in the impact simulations.