Valve leakage online detection system and method

The invention discloses a valve leakage on-line detection system and method, and the system comprises a pressure sensor which is disposed at a position, close to a filler, in a valve, and is used for collecting a filler pressure value, close to the filler, in the valve; the differential pressure sensor is used for being arranged at a middle cavity and a connector in the valve and used for collecting the upstream pressure value and the downstream pressure value of the valve; the detection device comprises a detection unit and a support, the detection unit is installed on a pipeline connected with the valve through the support, the pressure sensor and the differential pressure sensor are both electrically connected with the detection unit, and the detection unit determines whether leakage exists in the valve or not according to the filler pressure value, the upstream pressure value and the downstream pressure value. The sensors are arranged near the internal interface, the middle cavity and the filler of the va