Abstract: The aircraft featuring high wing and low horizontal tail encountered local flow sepa-ration at the lower surface of the horizontal tail near the root,which manifests itself as aircraft vibration and abnormal pitching moment.The proposed solution is to install a pair of winglets of small aspect ratio and reversed camber at 0.12 root chord ahead of and 0.30 root chord below the horizontal tail.The winglets function as vortex generator/guiding vane,which enhance the ener-gy exchange between the boundary layer and the outer flow in the separation zone,and also re-duce the local absolute angle of attack of the root section of horizontal tail by the induced up-wash.The numerical simulation and wind tunnel tests reveal that the optimized vortex generator can reduce the separation area by 50%,and delay the starting angle of pitching moment crank by more than 4°.Therefore,the problem of local separation is solved by relatively minor cost of per-formance and weight,and the boundary of flight is enlarged.