A 3D simulation model of dry-type air core reactors is established through the multi-physical-field coupling method based on an electromagnetic-temperature-structural field, and the electromagnetic distribution characteristics, temperature, and structural deformation of the reactor are analyzed. The inductance, temperature rise, structural deformation, and amount of metal conductors of the reactor are the optimization parameters. Initially, the sample data was obtained through the orthogonal test method and multi-physical-field coupling simulation; then, the VIKOR (Vise Kriterijumski Optimizacioni Racun) method was used to equalize and control the electromagnetism, temperature rise, structural deformation, and metal conductor consumption of the reactor. Finally, multi-physical-field coupling technique is used to verify the correctness of the method. The results show that the inductance deviation of the optimized reactor is 4.51%, the highest temperature and the maximum deformation of the encapsulation coil are reduced by 13.5% and 0.52%, and the metal conductor mass of the coil increases by 7.57%, which meet the design requirements.