In flexible roll forming, the horizontal movable sheet steel can be formed by controlling the servo motor to drive the multi-pass vertical movable roll. Only when the longitudinal movable distance of the roll in every pass matches exactly the contours of the sheet steel in time and space, the designated cross-section shape can be formed. Controlling the servo motor by applying the configuration programming is a common approach to achieve roll motion, but will not be able or difficult to realize by the configuration programming for complex contour without the rules such as hyperbolic, or the molding product in asymmetric cross-section shape, however, there are two other approaches such as simplifying the curves and using similar shapes to fit the process. As for the complex non-symmetrical curvature shapes, this paper adopts the variable time-domain servo motion control method to form the sheet steel. Experiments show that the variable time-domain servo motor control is a good motion control method for the sheet steel forming in complex cross-section shape.