Abstract: The assembly leak testing is necessary for space station, especially the on-orbit leak detection, which is very important to guarantee the safety of astronauts and the success of flight mission. The real-time overall leakage monitoring, the technologies of orientational and quantificational detection for the structural leak, the technique for astronaut leak testing outside the cabin, the method of leak repair are discussed in this paper. And the key technologies are analyzed. The systematic technology development can reliably guarantee the on-orbit leak protection for space station.