Abstract: The vacuum chamber of the magnetic confinement nuclear fusion device has a large volume, many flanged and welded structures, and long internal water cooling pipes. Under the combined action of thermal stress, electromagnetic force and neutron irradiation, the vacuum chamber has a great risk of leakage. Considering the influence of nuclear radiation on human body, the traditional leak detection method in vacuum chamber is no longer applicable in tritium operation condition. The leakage detection method of Tokamak vacuum chamber based on vacuum plume effect and the leakage detection method of Tokamak pipes based on molecular screen difference were proposed, which are used to detect and locate the leakage of water-cooled pipes in Tokamak vacuum chamber and the leakage of pipes in external window, respectively. The expe-rimental results showed that the two methods can accurately detect the leakage of the water-cooled pipes in the vacuum chamber and the leakage of the external window pipes connected to the vacuum chamber, and can realize a more accurate location, which provides a new scheme for the leakage detection of Tokamak involving tritium operation in the future.