Generally, a vertical rolling process is used to achieve extensive width reduction in hot strip mill. However, it is impossible to avoid the defects such as dog-bone and edge-seam defect. The sizing press process has been developed in response to the defects mentioned above. Especially, this study is carried out to investigate the deformation of slab by two-step sizing press. The deformation behavior of slab in the sizing press process is more favorable than that in conventional vertical rolling edger. The FE-simulation is applied to predict the deformation behavior of the slab. In this paper, the several causes of the asymmetrical deformation are mentioned for the purpose of understanding of the anvil shape. Load, dog-bone and edge-seam defect are discussed in width sizing process considering the anvil shape. And to reduce the problems generated at rougher mill just after sizing press, these are studied in this paper. The deformation behavior of slabs and optimum anvil shape are obtained by rigid-plastic finite element analyses and neural network.