Abstract: In order to verify the applicability of AUT to the inspection of pipeline automatic girth weld based on non-internal automatic welding machine, the AUT inspection process scheme was optimized by simulation, and the processing contrast test block and process weld were designed. The optimized AUT detection scheme is used to detect the process welds, and the supplementary detection is carried out by digital radiography (DR). The test results show that by optimizing the AUT testing process, the pipeline automatic welding by non-internal automatic welding machine can be detected, and different types of defects can be detected.