Abstract: Based on CFD (Computational Fluid Dynamics) discrete-time aerodynamic models and two degrees-of-freedom (DOF) analysis, aeroelastic responses of a thin plate with and without structural damping, which is placed in smooth flow and oscillates after initial excitation in vertical or/and torsional directions, are evaluated in this paper. The characteristics of aeroelastic displacements and self-excited aerodynamic forces, as well as the relationship among them are also presented. It is confirmed that the vertical and torsional oscillations would simultaneously occur, even though only one DOF excitation is applied. Additionally, at low reduced wind speed, the effect of coupled aerodynamic force on aeroelastic response is not notable, and the aerodynamic force can provide more aerodynamic damping to the aeroelastic system on vertical DOF than on torsional DOF. It is found that both the system’s vibration modals are involved in each DOF aeroelastic response as well as in the aerodynamic forces. It is also found that the oscillation of a thin plate with a system frequency is one kind of embroiled oscillation, which combines a dominating motion in one DOF with a secondary motion in another DOF.