Hot rolling of a large ring of titanium alloy (LRT) is a highly nonlinear incremental forming process with coupled mechanical and thermal behaviors (MTBs) which significantly affect microstructure and properties of the ring. The feed rate of idle roll and the rotational speed of driver roll have major effects on ovality of the ring. In this paper, the effects of these parameters on the ovality of the ring have been investigated by a coupled thermo-mechanical 3D-FEA. The results show that the ovality of ring blank decreases with the increase of the rotational speed of driver roll or the decrease of the feed rate of idle roll. The results obtained can provide a guide for forming parameters optimization.