Abstract: The leakage of pressure pipes will usually cause accidents and pollution to environment. The leakage of pressure pipes can be monitored on line with acoustic emission (AE) technology, so the leakage sources can be detected in time. Through establishing AE testing system on leakage of gas pipeline, the amplitude, energy of AE signals from leakage are studied, also are the rules that spectrum changes with the change of pressure, propagation distance and diameter of leakage hole. All of these provides experimental evidence for application of AE technology on the leakage of the pressure pipes.