Multiple forging cycles are required to reach a steady-state temperature distribution in forging dies, which can lead to thermoelastic deformation and impact on the dimensional accuracy of the final forging components. The steady-state temperature fields of a three-layer combined die with constant, convection, conduction and convection thermal boundary conditions were determined in the present study. Thermoelastic deformation and the contact stresses between layers were directly related to geometric and material properties, external stresses and the temperature distribution. Warm/hot and cold forging case studies were studied using finite-element analysis. In warm/hot forging, the contact stress of the steady-state temperature distribution was smaller than the hypothetical non-uniform temperature distribution. During cold forging, the difference in total deformation between steady-state and uniform temperature distributions at the same temperature was 0.025 mm, which may reduce the geometrical accuracy of cold forging parts.