During inelastic buckling and according to the deformation theory of plasticity, Poisson’s ratio varies in the elastoplastic region of stress-strain curve as well as the other parameters such as secant modulus and strains. In this study, the inelastic buckling equation of plate are perfectly developed due to variation of Poisson’s ratio when the plate is subjected to multi axial loads. Using generalized integral transform, this equation is solved for simply supported plate and the results is compared with those in which Poisson’s ratio is ½ (the incompressible value for isotropic materials). The results show that the inelastic buckling loads is generally decrease and for thicker plate, the differences significantly decrease.
