The utility model discloses an adjustable valve sealing device specially used for a high-voltage cable. The adjustable valve sealing device comprises a sealing main body with the cable sleeved in, a valve disposed at one end of the sealing main body, and an air nozzle disposed on the valve; the other end of the sealing main body is provided with a circular hole for sleeving the cable into the sealing main body, and the joint position of the circular hole is sealed by lead seal to form a sealed state; and the air nozzle is connected with a vacuum pump via a rubber tube. An appropriate size of the sealing main body is selected according to the external diameter of the cable, the valve facilitates stop and start operation during an operation process, and the stop and start operation can be carried out at any time. After the sealing main body with the appropriate size is made according to the external diameter of the cable, the installation process is very simple, a waterlogged cable is sleeved into the sealing main body, sealing processing is carried out in a lead seal manner, the air nozzle is connected with the vacuum pump via the rubber tube, and a whole vacuum-pumping device is started for vacuum-pumping.