In this paper, experimental and numerical analysis on leakage through the heater inner tube, inner tube, with the study of leakage pressure leakage aperture size, propagation distance and the outer tube of liquid acoustic emission signal of the status and characteristics of acoustic emission signals of the mapping relationship, through the change of the above four factors, the leakage fault diagnosis rules derived from the heater, for better application in the heater pipe leakage online fault detection.