Abstract: This paper has made an approach to calculate the natural frequencies of the transverse vibration for four-high mill stand in accordance with acymmetric models of six degrees of freedom. In this paper the work roll and back-up roll are taken as elastic bodies which cross-sections are variable. Based on the energy method, the calculation problems of both masses and stiffnesses in the models are solved, and formulae are given for calculation the natural frequency of four-high mill stand. Experiment shows that the natural frequencies got from theoretical formulae are good approximations compared with the values measured.