This paper focuses on the design of eleven rollers straightener. An elasticplastic FEM model is introduced to cope with the difficulty of preestimating the performance of straightening during the design process. To obtain straightening force, stress, strain, elasticplastic ratio, relations between reduction amount of roller and roughness of plate per square meter, a threedimensional element model is established and straightening process is simulated. In addition, an experiment is conducted to measure the reduction amount of roller and the roughness of plate per square meter. It is shown that the results of numerical simulation are consistent with the experimental results. The developed computing model can provide essential references for the optimization of straightener.