Abstract: Aiming at the surface spalling failure of rollers,the distribution law of contact stresses between the working roll and the back-up roll of a four-high-mill was simulated with nonlinear finite element method considering the different material microstructure and performance between hardening layer and core of rollers.Comparison of the available simulated results with the theoretical predictions using traditional strength check method indicates that the contact stresses between rollers,maximum shear stress below the back-up roll surface and its acting depth were all greater than the theoretical predictions of Hertz's formulas,which is very important for discovering the failure mechanism of rollers.