Owing to the elasticity, the large deformation was brought in the high aspect ratio wing in the flight. The large deformation had a great influence on the flight performance. In this paper, the loosely coupled method was used for the research of high aspect ratio wing aeroelastic problems. The Navier–Stokes equations were solved for fluid domain computation, and the nonlinear finite element method was adopted for solid domain computation. The data exchange program and mesh regeneration progress were adopted for fluid–structure interface problem. Finally, the aerodynamic characteristics of high aspect ratio wing were obtained under different fly conditions. In addition, to validate the proposed method, the flutter analysis of AGARD 445.6 wing is carried out and compared with the experimental data. The numerical result validates the proposed computational fluid dynamics/computational structural mechanics method.