Abstract: The mechanical characteristics of the centrifugal effect of bristle are crucial for the design of rotating brush seal structures and the analysis of sealing performance. The bristles are installed in the inner and outer rotors of the two kinds of rotating brush seal structures between counter-rotating shafts was designed, and the theoretical formula of centrifugal deformation of bristle for rotating brush seal between counter-rotating shafts was derived. The numerical model of mechanical Characteristics of bristle was established. After verifying the accuracy of the numerical model, the effects of bristle installation angle, bristle diameter, and bristle length on the mechanical deformation characteristics and stress distribution characteristics of the rotating brush seal of the two installation methods were studied. Finally, the applicable characteristics of the two installation methods of rotating brush seal were compared and analyzed. The results show that when the bristles were installed in the inner rotor, the sealing clearance decreased as the inner rotor speed increased, which improves sealing performance. When the bristles were installed in the outer rotor, the sealing clearance increased with the increase of the outer rotor speed, which is not conducive to the sealing performance. The bristle deformation and root stress were reduced by reducing the bristle installation angle, increasing the bristle diameter, and reducing the bristle length. When the rotor speed is 7700 r/min, the deformation of the bristle in the radial direction of the rotor was increased by 67.1% after the bristle installation angle of the bristle was installed on the inner rotor was increased from 30° to 40°. When the bristle diameter of the bristle was installed on the outer rotor increased from 0.07 mm to 0.10 mm, the deformation of the bristle in the radial direction of the rotor was reduced by 57.4%, the bristle length decreased from 11.9 mm to 11.5 mm, and the stress at the root of the bristle decreases by 9.1%. When the bristle was installed in the inner rotor, the sealing clearance between the bristle-free end and the outer rotor decreased as the inner rotor speed increased. However, when the bristle was installed on the outer rotor, the sealing clearance increased with the increase of the outer rotor speed. The bristle installation angle and bristle diameter are the main factors affecting the centrifugal deformation and stress distribution of the bristle. At identical rotational speeds, the deformation and root stress of bristles installed in the outer rotor exceeds those of bristles installed in the inner rotor. Considering both sealing performance and service life, it is recommended to install the bristles in the inner rotor.