To reduce the probability of helicopters being discovered during mission execution, based on the geometric optics method and consistent diffraction theory, the effects of different tail rotor airfoil thickness, curvature, and scissor angle of tail rotor on RCS were studied for the helicopter tail rotor. Using radar to irradiate the tail rotor from the ground and radar to irradiate the tail rotor from the rear of the helicopter, the RCS of the tail rotor is analyzed using two different irradiation radar orientations. By comparing the RCS peak and mean values of different parameters of the tail rotor, the more favorable conditions for the stealth of the helicopter tail rotor are determined. When illuminating the tail rotor from the ground, the RCS with small thickness and curvature of the tail rotor will be smaller, and changes in the angle of the scissors will cause changes in the peak phase of the RCS. When the radar illuminates the tail rotor from the rear, the RCS of the tail rotor with smaller thickness is smaller, while the RCS peak of the tail rotor with larger curvature is smaller. Based on comprehensive analysis, the smaller the thickness and curvature of the tail rotor, the more favorable it is to reduce the RCS of the helicopter tail rotor.