Abstract: The numerical study of the impact of small-particle-perturbation on the nose tip where the circumferential angle is ±45°on yaw characteristics of aircraft at high angles of attack is introduced.The results demonstrate that the small-particle at the circumferential angle of ±45° has great impact on the yaw characteristics,and it helps to fix the direction of the side force and yawing moment.On basis of the flow vortices structure observation,it is shown that the vortex sheds from the side of small-particle is stronger than the other one on the opposite side,and this vortex induces a stronger separation bubble on the lateral side of the forward fuselage,which lead to large side force at high angle of attack.