Abstract: In order to test the leakage of the electric propulsion spacecraft after the xenon being filled, the leak detection methods and the key technologies are studied. A leak detection system is developed based on the gas chromatography (GC). It is verified by the experiments to be reliable. The result shows that the leak detection system could detect the leak of qualitative analysis and quantitative analysis for the leak of spacecraft (1.0×10^-5~5.0×10^-2 Pa·m³·s^-1), when the range of the volume fraction of xenon is 1×10^-7~5×10^-4 in the air. If the volume fraction of xenon exceeded 5×10^-4, it could confirm that the spacecraft had a huge leak (the leakage >10^-2 Pa·m³·s^-1). This system could satisfy the leak detection requirements of the electric propulsion spacecraft.