Abstract: Abstract: Objective To construct 3-D finite element model of craniofacial complex in rapid maxillary expansion so as to provide biomechanics research platform for evaluating the stress distribution and displacement change rule of craniofacial complex in rapid maxillary expansion. Methods Using CT scan, and softwares of Mimics10.0, ProE Wildfire 4.0, MSC.Marc.mentat 2005R3 and Geomagic Studio10.0, the 3-D finite element model of craniofacial complex with solid models of maxillary first premolar, first molar and its periodontal ligament as well as the band was developed. Results A 3-D finite element model of craniofacial complex was constructed, which included 522800 elements. The model had good comparability with the morphology and quite precise mechanical characteristics, which could be imported to CAD. Conclusion The method to develop a 3-D finite element model of craniofacial complex in rapid maxillary expansion using CT, Mimics10.0, MSC.Marc.mentat 2005 R3 and Geomagic studio10.0 is feasible and effective, which can be used for biomechanical analysis of RME.