Abstract: According to the characteristic of adjusting width by erect roll at PZH Steel, the uneven deformation rule of slab during erect and horizontal rolling was analyzed by finite element simulation on base of MSC. Marc software. The effect of rolling process conditions on the width and size of head and tail of interim slab were also analyzed by numerical simulation. Trie results of simulation are accord with practical values. These results are helpful to find out some measures for hot rolling plant to decrease chip-off and increase incoming ratio.