Abstract: The mathematical model of transversal mill modulus of the cold rolling four high mill is established by the program which the structure of model is determined on the principle of beam on elastic foundation, and the correcting factor of model is obtained by statistical analysin of experimental data. Thu. combined with the studying of hot roll camber, the equation of transversa sheet profile after rolling is proposed, which can reflect the physical rule correctly, is simple in construction with certain accuracy and is permitted online application in strip flatness control system