Abstract: The cage forming process of ERW straight-welded pipe is simulated by means of the large-scale, nonlinear finite-element analysis software Marc. As a result, the shape of the formed pipe blank is obtained, and so are both the equivalent stress and the stress field distribution at the cross section of each individual roll stand and along the strip longitudinal direction. Moreover, the contact state between the cage roll shaping surface and the material is analyzed, which could provide theoretic reference for pass design and cage roll set up of the straight welded pipe mill.