<p>Because of the extremely complicated structure of ultra-large beam blank mold, a major challenge in its water-cooling structure design is the uneven deformation and stress distribution caused by the high temperature at the fillet and uneven temperature distribution of the copper plate, which will significantly affect the service life of the mold under complicated thermal/mechanical loads. The first three-dimensional mechanical model of the ultra-large beam blank mold was developed using the bilinear isotropic hardening and creep models. The simulation results of the pre-developed interface heat transfer and mold-cooling water system models were used as the boundary condition of the mechanical model to complete the sequential coupling of the series of models. The reliability of the model was verified by comparing the model prediction results with the on-site measured results. Based on this model, the total deformation, directional deformation and stress distribution of the mold copper plate under different water-cooling structures were investigated. The results show that the temperature, the type and shape of the water-cooling structure are important factors affecting the deformation and force behaviors of the copper plate. The U-shaped water slot of the narrow face and the water hole with a diameter of 10&#xa0;mm of the wide face can minimize the stress and deformation of the copper plate, and the tensile stress and shear stress of the bolt, ensure the stress distribution and deformation of the copper plate more even, which is helpful to improve the service life of the ultra-large beam blank mold.</p>