The Peters model is used to simulate the linear aerodynamic force and ONERA stall model is used to simulate the nonlinear aerodynamic force. The state-space equation of the aeroelastic system is established by coupling the structural equation. In order to solve problems, Euler predictor corrector method is used in the time domain and eigenvalue analysis method is used in the frequency domain. The case of dynamic stall is simulated based on Peters-ONERA model and the results imply that the validity of the aerodynamic model. The effect of under relaxation iteration on the stability of static aeroelastic solution is studied. It is found that under relaxation iteration can improve the static aeroelastic solution stability. Then based on frequency and time domain methods, flutter critical characteristic and bifurcation phenomenon are studied. It is found that:(1) Under large angle of attack, the coupling between nonlinear aerodynamic modal and structure modal could induce the instability of the structure modal and single degree of freedom flutter. (2) Under different angles of attack, bifurcation characteristic of aeroelastic system is far different. (3) The sensitivity to the disturbance of the system is different in different ranges. When the disturbance increases, the aeroelastic system will change from stable state to limit cycle oscillation.