In order to research the effect of metal flow between web and flange, the concept of extension coefficient used to judge the deformation degree for rolling H-beam, through the method of changing the extension coefficient, the finite element model was established by the platform of CAD software. Defining boundary conditions, geometric properties and contact situation, and input initial conditions based on the model. It can gain the displacement cloud map and displacement curves of the model by computer simulation. Based on the simulation results, studying the effects of different extension coefficient on metal flowing between flange and web, as well as the qualitative relations of extension coefficient between flange and web. The results showed that with the enlargement of extension coefficient, the metal flowing between web and flange would be more obvious, while the definite feature relation between web and flange can get better effects with the condition that the extension coefficient of flange is large than that of the web.