In the present work, an analytical investigation is introduced to determine the aeroelastic behavior of unswept, rectangular wings simulated by cantilevered composite plates using energy formulation and incompressible aerodynamic theory. Modified higher order shear deformation theory is used in the structural formulation. Doublet point method is used to solve the subsonic unsteady flow over the proposed rectangular wing. The flutter and divergence velocities are obtained using U-g method, which are validated by the analytical, finite element, wind tunnel test results available in the literature. The effect of composite fiber orientation on natural frequency, flutter and divergence speeds is discussed.