In this study a new numerical-analytical method for elasto-plastic and plastic modelling and simulating of FG beams is presented. The functionally graded (FG) beam composed of ten layers through the thickness and it is assumed that the mechanical properties of the beam vary through the thickness described by a simple power law distribution in terms of the volume fractions of constituents. The beam is assumed to be under transverse pressure load. In this paper a new method is presented based on linearization of the nonlinear part of the stress-strain curve of the material of the layers of the FG beam and using the elastic relations for bending analysis of beams. Numerical results for functionally graded beam are given and results of this paper for homogeneous beam are compared with other methods and good agreement is obtained between them. In addition, the effects of material properties on the stress field through the thickness of the FG beam are determined and discussed.