With increasing casting speed, the residence time of a billet in the secondary cooling zone decreases, the heat derived per unit time increases, and the ability of the solidified billet shell to withstand various strains decreases. To study secondary cooling support guidance technology for high-casting speed billets, 3D creep finite element bulging calculation software was developed on the basis of elastic mechanics. The bulging volume of a billet can be accurately predicted via a viscoelastic creep model, which can be used to determine the optimal clamping length and provide a useful reference for the roll design of high-casting-speed continuous casting machines. On the basis of the production statistics data, the design criterion of foot roll is proposed; that is, when the casting speed exceeds 5.2 m/min, an independent dense guide roll segment should be added to effectively control the bulging deformation for the production of a 160 mm×160 mm cross section of an ordinary carbon steel billet.