Abstract: A new fast calculation method is proposed based on the influence function method for the elastic deformation of multi-roll mill. The shortcoming of the traditional influence function method is analyzed and the new matrix iteration method (MIM) is developed for the deformation calculation of multi-roll rolling mill system. The method offers significant improvements in accuracy, robustness and calculation workload, which is suitable for any type of multi-roll mill. According to MIM, the assembly stiffness matrix of Sendzimir mill is given and the characteristics of the stiffness matrix are discussed, then the iterative calculation process is listed. Roll system deformation model of Sendzimir mill is built by FEM software and the results of both MIM and FEM are compared with different work conditions. The comparison of the roll displacement verifies the reliability of MIM.