A water-lubricated stern tube seal is a breathable type of stern tube seal used for high-speed vessels in the marine field. It includes a stern tube and a stern tube seal, where the stern tube is connected to the stern tube seal at its front end. The stern tube seal features an inlet, differing from others in that it has an air vent at the top of the stern tube or the top of the stern tube seal, which is connected to an exhaust pipe. The beneficial effects of this utility model are: 1. By opening the exhaust pipe, air in the stern tube can be promptly discharged, preventing the formation of air pockets, ensuring smooth water flow through the stern tube with sufficient flow rate. This guarantees that the sealing components within the bearing and stern tube seal are submerged in water, thereby avoiding overheating and damage to the stern tube and seal, enhancing the reliability and effective service life of the shafting system; 2. The structure is simple, and it can be implemented by simply opening an air vent at an appropriate location on the top of the existing stern tube seal, making installation and maintenance convenient.