This standard specifies the terms and definitions, general requirements, flaw detection equipment, comparison samples, selection of plate wave modes, flaw detection methods and defect assessment of metal sheet metal plate ultrasonic flaw detection method. This standard applies to ultrasonic plate wave flaw detection of metal plates whose thickness is not more than 5 times the wavelength of the surface wave of the tested plate, but it must be confirmed that the sound wave excited is indeed a plate wave, and the flaw detection can be carried out with sufficient flaw detection sensitivity.