In order to establish acoustic emission attenuation location model of pressure pipeline leakage， it is necessary to carry out experimental research on acoustic emission of pressure pipeline leakage to master the propagation characteristics of acoustic emission signal on metal pipeline. It is necessary to obtain the propagation characteristics and differences of acoustic emission signals in metal pipes with different wall thickness and outer diameter for the same material， processing technology， different wall thickness and outer diameter， so as to reveal the influence of metal pipe wall thickness on acoustic emission wave propagation attenuation. In this paper， three kinds of metal pipes with different sizes and specifications are used as the test objects， and the acoustic emission detection technology is used to obtain the attenuation law of acoustic emission signal along the metal pipe wall with different wall thickness， and the influence of metal pipe wall thickness on acoustic emission wave propagation is revealed. The results show that the attenuation characteristics of the acoustic emission signal vary with the thickness of the pipeline. In the thin-walled tube， the mode conversion occurs in the propagation path of the acoustic emission wave， that is， the dispersion phenomenon occurs. The superposition of the waves of various modes makes the signal amplitude not monotone attenuation along the propagation path. This must be considered when the attenuation characteristics of the acoustic emission signal are used for positioning.