Abstract: This article generally described the site detecting procedure of Phased Array Ultrasonic Testing (PAUT) for pipe butt welding, explained the problems existing in the Phased Array Ultrasonic Testing (PAUT) for pipe butt welding data interpretation via the comparison of PAUT result and RT result. Meanwhile, according to the interpretation results of a great deal of site test data, preliminary studies and summarizations of the improvement of this kind of PAUT data interpretation method were presented.