The present bending process of elliptic cyclical surface is bended into a cylinder first, and then pressed into an elliptic cyclic by a pressing machine. However, the elliptic shape can not be controlled accurately because the bigger elliptic cyclic rebound after pressing. The curvature radius of the elliptic cyclic needed is determined by the position of the upper, bottom and the two side rollers. The model of each roller`s position and the wanted curvature were built, and the arc length and curvature at each point of the ellipse were real-time calculated, thus the bending process was achieved by the real-time control of the two side rollers displacement according to their arc length and curvature. The model was practically applied in the four-roller bending machine, and the elliptic cyclic could be perfectly and accurately bended.