The invention discloses a sewage discharge management system which comprises a shipborne positioning system, a ship automatic blowdown valve system, a shipborne communication system and a central data center. The shipborne positioning system is used for positioning a ship and sending a signal to the ship automatic blowdown valve system, the ship automatic blowdown valve system is used for processing information and sending processed information to the shipborne communication system, and the shipborne communication system also sends the data to the central data center. The sewage discharge management system has the main advantages that a shipborne global positioning system combines with an electronic chart, whether pollution discharge can be performed in the sea area the ship is located; mechanical locking and a magnetic valve are combined, and illegal pollution discharge is effectively and completely eradicated; the pollution discharge time and flows are reported and transmitted back in real time, and unified supervision is achieved. In addition, the device manufacturing process is simple, and the safety is high.