Objective To establish three-dimensional finite element model of the repair for orbital defect with Medpor implant, and to explore biomechanical characteristics including displacement and stress analysis of Medpor implant with the state of implantation in orbital floor, in order to provide the reference basis for surgeons. Methods The three dimensional model was established by Mimics software via reading the CT data of DICOM format of a patient with left orbital floor fracture. Followed the 3D model remeshing by Magics finite element software, material properties assignment with gray value conversion, the three-dimensional finite element model for the repair of orbital defect with Medpor implant was modeled. Then displacement and stress analysis of Medpor implant was done by finite element method under the load of different simulated gravity: no fixation, one and two screws fixation. Results The finite element was established in this study successfully.No fixation between Medpor implant and orbital wall allowed large displacement with no stress. Fixation by one screw or two screws has the same stress value. Conclusion Three-dimensional finite element model of the repair for orbital defect with Medpor implant was established firstly. According to finite element method, the screw implant can play a good role in the fixation of Medpor,and fixation by one screw or two screws has the same effect.