Abstract: The application range, grade and evaluation and acceptance method of index of the latest edition of the international standard Non-destructive Testing of Welds-Phased Array Ultrasonic Testing-Acceptance Level are introduced, and the two ways of acceptances, i.e. one being based on measuring the length and height and the other based on measuring the length and the maximum amplitude, are analyzed. It provides a technical reference for the establishment of acceptance criteria for phased array ultrasonic testing of welds in the future.