In order to investigate the aerodynamic characteristics and aerodynamic stability of the two degree-of-freedom（2-DOF）thin plate undergoing large-amplitude oscillation，the governing equations for arbitrary-deformed fluid domain in the two-dimensional incompressible form are numerical solved based on the Arbitrary-Lagrangian-Eulerian description and the finite difference method in moving-grid system. Then，computational fluid dynamics（CFD）is employed to simulate the flow field around the thin plate undergoing heave and/or pitch oscillation at various reduced wind speeds. The research finds that the aerodynamic system around the thin plate is linear and stability when the thin plate experiences small-amplitude vibration in heave or pitch，and it is also linear and stable even when the thin plate undergoes large-amplitude heave motion. However，when the thin plate undergoes large-amplitude pitch motion，the aerodynamic system of the thin plate presents nonlinearity which will become significant and even turn into instability with the increase of reduced wind speed. Meanwhile，when the thin plate experiences 2-DOF oscillation with large amplitude in pitch coupled with different amplitude in heave，nonlinearity will also be presented and be more significant with the increase of reduced wind speed. It is noted that such nonlinearity is generated from the large-amplitude oscillation in pitch. For the coupled vibration system with 2-DOF，when the vibration amplitude is small while the reduced wind speed is high，its aerodynamic system is instable. While when the vibration amplitude in heave is large，the aeroelastic system will be stable.