Abstract: The dissymmetry of flatness control in the vertical direction is the characteristic of a DSR (dynamic shape roll) mill. By constructing the finite element model for whole rolls, the flatness control behavior was numerically calculated by using ANSYS software. After evaluating the flatness control behavior and the vertical dissymmetrical characteristic of a DSR mill in China, the reason for dissymmetry was pointed out, and the measures of moderating the dissymmetrical harms to shape was proposed.