Abstract: The relation between primary and actual velocity reference of a flying shear is discussed during three successive phases including start-up acceleration, as-sheared constant velocity and after-shear returning/positioning. Such technological indices as shearing precision and positioning accuracy of flying shear and smoothness of cut end face of workpieces all depend on the relation between the two velocity references. The relation shall be calculated and output on computer, and it has been applied to some steel rolling mills. The applications show that the actual velocity reference of flying wheel is easy to implement on computer and quite accurate.