Abstract: For the requirements of offshore platform acoustic emission nondestructive testing, this paper obtains the propagation rules and differences of the metal pipes with different diameters and the differences with metal plate, reveals effects of the pipe diameter on propagation characteristics of acoustic emission waves, through the research on propagation characteristics of acoustic emission wave of metal pipes of the same wall thickness but with different diameters, comparison was made of propagation characteristics between the pipe and the plate taken as the limit case of the metal pipe. Pipe structures and plate structures are important parts of the offshore platform, so the research of this paper is of significant engineering application value to improve the positioning accuracy of fault sources and the analysis of fault characteristics in application of the offshore platform acoustic emission testing technology.