Abstract: To investigate the deformation behavior of plate steel during roller leveling in depth, the curvature integration by elastic-plastic differences was introduced to simulate and analyze the effect of plastic deformation rate on the leveling results. A method of dispersion calculation was proposed for plastic deformation rate, thus getting the relationships between the plastic deformation rate, residual curvature and average residual stress for different combinations of reduction schedule under conditions of single-valued initial curvature. The plastic deformation rate cannot be justified theoretically that it is the only criterion for leveling results. However, because the initial curvature is very hard to determine on line, the plastic deformation rate has to come up to about 80% after roller leveling. In addition, the optimized leveling conditions are pointed out for the single-valued initial curvature.