Abstract: Aiming at the break-down rolling process of GCr15 bearing steel 320 mm×480 mm rectangular billet rolled into 150 mm×150 mm intermediate billet, the temperature and deformation during the break-down rolling process were simulated with finite element method, the temperature variation law during rolling and the influence of temperature gradient on deformation permeability under different descaling and cooling conditions were analyzed. The results show that the established simulation model can accurately simulate the temperature distribution of multi-pass reciprocating break-down rolling; the larger the temperature gradient of billet section is, the easier the deformation will penetrate into the center of billet, the improvement of deformation permeability can improve the quality of large size bearing steel bar center.