Abstract: The crown-flatness vector method is applied to the computation of plates' drafting schedule to control effectively the plate crown/flatness and make full use of mill capacity. Analyzing a simple plate crown model and giving an on-line model relevant to it, the mechanism of crown-flatness vector method is discussed, as well as the related plate rolling technology in lengthening phase. Then, the computation for drafting schedule in the phase can break down as three steps below. Decrease the number of several primary rolling passes by way of taking heavy reduction as possible. Take advantage of crown-flatness Vector method to control the crown/flatness of workpiece for the subsequent 3 or 4 passes. Finally, adjust the total number of passes or the coefficient of ultimate rolling force so as to enable the plate gauge of the exit of last pass to be equal to target gauge. The online applications for long time showed that the method can strongly control the plate shape and is available for on-line control of the plate shape and is available for on-line control of plate rolling process by computer.