The invention relates to a sleeve assembling centering device. The sleeve assembling centering device is arranged in a hollow composite insulator and comprises a first plate body and a second plate body, wherein the first plate body and the second plate body are parallel to each other and can be detachably connected. A first through hole is formed in the first plate body, a second through hole isformed in the second plate body, the first through hole and the second through hole are coaxially arranged, and a plurality of abutting parts are separately formed on the periphery of the first platebody and the periphery of the second plate body. When the sleeve assembling centering device is arranged in the hollow composite insulator, the abutting parts abut against the inner wall of the hollowcomposite insulator, and the first through hole and the second through hole are coaxially arranged with the hollow composite insulator. The sleeve centering device can effectively maintain the coaxiality among a conductive tube, a core and the hollow composite insulator, solve uneven distribution of a product electric field, a thermal field, a force field, stress concentration, unreliable currentcarrying and sealing performance and other quality problems due to the fact that the conductive tube, the core and the hollow composite insulator cannot maintain the concentric position, and ensure the product quality.