A sleeve assembly is disclosed, including: a sealing rubber plug, a sleeve body, a locking nuts, and a fastening wrench. The sealing rubber plug includes a rubber plug body, a through hole is disposed in the rubber plug body, and a cable that needs to be inserted into a device can be inserted into the through hole. The sleeve body has two opposite ends, a sealing ring is disposed on one end of the sleeve body, and a hollow bolt head is disposed on the other end of the sleeve body. The sleeve assembly can implement a cable protection function when the device requires high-density cable routing. Surface space of the device is not occupied during cable mounting, and mounting efficiency is high.