<p>The four-point bending test of curved beams is widely used to determine the interlaminar tensile strength of composite curved beams. The existing linear beam model provides an analytical solution for the test, while it fails in accurately capturing the full extent of nonlinearities under large deformations. Therefore, the nonlinear corotational beam model is developed in this paper to obtain the load–displacement relation. Combining Green–Lagrange strain and shear-deformable elements, the corotational approach provides an efficient and accurate solution for large deformation problems with small strains. A key innovation of the developed model lies in simplifying boundary conditions and introducing an efficient iteration method that separately handles varying contact points and angles, thereby significantly improving the numerical convergence and reducing computational cost. The accuracy is validated through comparison with finite element two-dimensional models, showing high consistency in deformation and the load–displacement relation. Furthermore, the error in the existing analytical linear beam model is analyzed and quantified.</p>