Abstract: To enhance the mechanical and thermodynamic performance of submerged arc furnaces, this paper addresses the low efficiency induced by thermal stress concentration and uneven flow in furnace flues. A three-dimensional geometric model containing the furnace body, electrodes, lining and flue duct is developed. Multi-physics coupled thermal-stress simulations are performed via ANSYS, combined with scaled model experimental research. Simulation and experimental results reveal that the flue duct of the unoptimized furnace presents obvious temperature attenuation, and severe stress concentration exists in the furnace lining. After structural optimization, the flue outlet temperature rises by 14% with a more uniform temperature distribution. Meanwhile, the stress and strain state of the furnace body is ameliorated, and the waste heat recovery efficiency is substantially boosted. The research findings provide a scientific reference for structural optimization, energy conservation, consumption reduction and safe operation of submerged arc furnaces.