Objective To determine the optimal layout of mandible implant fixation plates by topological optimization, and design personalized mandible implant fixation plates with high bearing capacity. Methods Taking a typical defected mandible as an example, the finite model of mandible was constructed with consideration of the properties of bone and scaffold materials. Topology optimization analysis of the model was carried out, and personalized mandible implant fixation plate was designed. The stress distributions of the mandible, plate and screw in conventional and personalized plate system were simulated to evaluate mechanical characteristics of personalized mandible implant fixation plate. Combined with Gibson-Ashby model, the porous face-centered cubic lattice structure prosthesis with elastic modulus equivalent to cortical bone was designed, and the final scaffold scheme was finally determined. Results The peak stresses of the mandible, fixation plate and screws of personalized mandible implant fixation plate system were 55.86, 291.1 and 122.53 MPa, respectively, which were 9.8%, 32.0% and 14.6% lower than those of conventional fixation plate fixation system. Combined the personalized mandible implant fixation plate with porous structure, a three-dimensional (3D) porous scaffold model with an optimal porosity of 71.6% was obtained. Conclusions The personalized mandible implant fixation plate designed in this study significantly reduced the peak stress and improved the reliability of the scaffold. Combined with selective laser melting (SLM) technology, personalized prosthesis with excellent properties can be quickly manufactured to meet tight time requirements.