<p>To accurately characterize the rolling force and exit thickness ratio of bimetallic composite plates under the combined influence of gradient temperature and deformation during the rolling process, we propose a thermomechanical coupling calculation method based on the finite difference method (FDM). This approach accounts for the effects of non-uniform distributions of strain rate, strain, and temperature on the deformation resistance of elements during rolling. The deformation zone of the plate is discretized into multiple elements along the thickness and rolling direction. Initially, a two-dimensional finite difference method (2D FDM) is employed to determine the strain rate, strain, and temperature field distributions of the composite plate, which are then used to construct the deformation resistance matrix of the elements. Subsequently, using Orowan’s non-uniform deformation theory, we analyze the rolling process of the composite plate, introducing a Coulomb friction assumption at the interface between the two plates to form the corresponding differential equations. Finally, the deformation resistance matrix is applied to the deformation elements, facilitating the coupling of the two physical fields and deriving a computational model for the rolling force and exit thickness ratio of bimetallic composite plates under gradient temperature rolling. Using the hot rolling of stainless steel/carbon steel composite plates as an example, we validated the mathematical model through experiments and Abaqus finite element simulations. With errors under 10% under the same parameters, the mathematical model’s accuracy and effectiveness were confirmed, providing a theoretical basis for mill design and process parameter settings.</p>