Abstract: In terms of the combination of patched grid and domain decomposition techniques, the N S equation of the complex flow around a wing body combination with deflection of control surface (aileron) is solved. In the computation Van Leer's scheme is employed to discretize the inviscid flux terms and the viscous flux terms are discretized by adopting central difference scheme. An internal coupling condition satisfying the conservation of flux is used on the interface of neighboring regions. Numerical results show that the present method is effective one for solving the flow around a wing body combination with control surface deflection.