Abstract: In the width reduction stage of a hot continuous rolling mill, the cross-sectional "dog-bone" shape of the slab varies with the amount of reduction applied by the width reducer(sizing press). This variation leads to significant differences in shape recovery during subsequent flat rolling, ultimately impacting the precision of final width control. Therefore, understanding the metal flow behavior during roughing-width reduction is essential for improving flat-rolling width control and provides a theoretical foundation for high-precision control in downstream processes.This study investigates the influence of the deformation resistance gradient—governed by side pressure, initial thickness, and material properties—on metal flow during large-strain deformation. A finite element model of the Short-Stroke Press(SSP) width reduction process was developed using ANSYS/WorkBench. The model was used to analyze the effects of key parameters on the dog-bone peak height, the central deformation zone, and the dog-bone deformation zone. A predictive model for the dog-bone shape was established. Furthermore, the stress-strain evolution during width reduction was examined to determine the influence of the deformation resistance gradient on free width spread after flat rolling.The results demonstrate strong agreement between simulation and field data. The errors for dog-bone peak height, central thickness, dog-bone deformation zone length, and post-deformation zone length are 1.82%, 0.65%, 1.43%, and 1.94%, respectively, validating the FE model. Compared to measured data, the predictive model improved accuracy for dog-bone peak height and deformation zone length from 96.31% and 96.53% to 98.68% and 98.32%, respectively. The prediction accuracy for central thickness and dog-bone deformation zone length reached 98.57% and 98.62%, confirming the model's effectiveness.The analysis indicates that while the deformation resistance gradient has a limited effect on the overall stress distribution, it exhibits a positive correlation with local stress magnitude. Specifically, a higher deformation resistance leads to increased width strain and greater deformation penetration depth, resulting in reduced free width spread after flat rolling.