An elastic-plastic stress analysis is carried out in a thermoplastic composite cantilever beam loaded by a bending moment at the free end. The orientation angle is chosen as 0degrees, 15degrees, 30degrees and 45degrees. An analytical solution is performed for satisfying both the governing differential equation in the plane stress case and boundary conditions for small plastic deformations. The solution is carried out under the assumption of the Bernoulli-Navier hypotheses. It is found that the intensity of the residual stress component sigma(x) is maximum at the upper and lower surfaces. The beam material is assumed to be strain-hardening. The Tsai-Hill theory is used as a yield criterion. The displacement components are found in the elastic region.