Abstract: The aeroelastic effect of flexible blades is becoming increasingly significant with the rapid development of wind turbines and the sharp increase in blade length. Based on blade element momentum（BEM） theory and multi-body dynamics theory, the aerodynamic structure coupling equation of 95 m blade is established, and the aerodynamic response of blades under extreme wind load is analyzed which include a detailed study of the vibration characteristics of the blades after flutter and the damping characteristics of the blades under different speed conditions. According to the research, negative damping oscillation is a key factor causing blade flutter instability.At the same time, the influence of density of air, pitch angle and other factors on the aeroelastic stability of large blades are analyzed by parallel comparison method.