A high-fidelity numerical simulation was presented for the flexible high-aspect ratio composite wing because of its high-speed nonlinear aeroelastic behavior. The fluid-structure interaction procedure used a loosely-coupled methodology. The compressible flow was modeled using the 3-D N-S equations on a deformable mesh, and the computational structural mechanics modeled in a steady analysis with geometrically-nonlinear effects. The transfer of distributed loads and displacements at the fluid-structure interface was based on detailed 3-D representations. Using this approach, a representative high-aspect-ratio composite forward-swept and backwards-swept wing were investigated for the steady flight conditions. Finally, the solution was implemented for the loosely-coupled fluid-structure interaction problem. Compared with the forward-swept wing, the lift coefficient of backwards-swept wing decreases obviously, the lift-drag ratio reduces markedly, which is obviously different from the rigid wing, so it must be considered during the design of a flexible wing.