In this study, the elastic-plastic stress analysis is carried out on symmetric laminated composite beam composed of four orthotropic plies. To determine analytically the residual stresses and the expansion of plastic zone for different stacking sequence, a software program is developed and this program makes it possible to establish elastic region, plastic region, the distributions of the elastic, elastic-plastic and residual stress components. The Bernoulli-Euler theory is utilized in the solution for small plastic deformations. For the elastic-plastic solution, the Tsai-Hill Theory is used...