Abstract: Though theoretical analysis,the variation rules of attack Angle of each blade airfoil during yaw operation were studied,and the airfoil pitch movement model was established. Then,the dynamic aerodynamic characteristics of the blade airfoil under yaw conditions were studied based on the LES method. The results showed that the attack angle of each blade section was changeable with approximate sine or cosine regularity when the wind turbines are running under yaw conditions. Different degrees of flow separation occurred with different spanwise positions of the blades,appeared dynamic stall phenomenon,and closer to the blade root,the dynamic hysteresis effect was becoming more obvious. The dynamic change of the separation bubbles of suction-side front edge leads to the pressure of which have vicious oscillation in small areas,which increases the instability of the flow.