In order to get high-precision TC4 alloy rod during the three-roll tandem rolling process, the spread of rod has been studied. A numerical simulation project was designed by an orthogonal experiment optimization design method. On the FEM software platform of Marc, the influence of rolling process parameters, including the rolling temperature, the rolling velocity, the inscribed circle of pass, the diameter of roller, and the friction coefficient between roller and rod, on the spread was investigated. Moreover, the effect order of above parameters was analyzed. On this basis, the spread model for TC4 alloy rod during three-roll rolling was established. The experiment was done on the self-developed three-roll mill of eight passes with a flat triangle-round sequence. The calculated results of spread model are in good agreement with the on-site data