Abstract: In order to find the cracks, corrosion and other dangerous defects of in-service tube trailer gas cylinders, and to guarantee the safe operation of the tube trailer, corresponding acoustic emission testing program was worked out based on the tube trailer gas cylinders structure, size, material characteristics. Furthermore, corresponding cracks, corrosion thinning and other artificial defects were machined and the whole acoustic emission testing was perforwed to the tube trailer gas cylinders. This paper simulated the crack, line corrosion, pitting corrosion and surface corrosion defects in four different results of the monitoring process and positioning, and the characteristics of acoustic emission source location, distribution and associated features were analyzed.