Abstract: This paper introduces the application of phased array ultrasonic testing technology in the butt weld inspection of long-distance gas transmission pipeline from the aspects of equipment selection, personnel requirements, process formulation, design and manufacture of simulated test pieces and the equivalence with the overall situation of radiographic testing. It is concluded that phased array ultrasonic testing technology has a high detection rate for common welding defects of long-distance gas transmission pipeline, and it can complement the advantages of radiographic testing in practical application. It has a certain reference value for the wide application of phased array ultrasonic testing technology.