Abstract: As the stress corrosion cracks possibly occurring on the turbine disc rim are concerned increasingly by various nuclear power plants vendors, it seems necessary to apply an improved inspection technology. The ultrasonic phased array(PAUT) technology, which possesses the advantages like large coverage, better detection capability and higher resolution than the conventional pulse-echo UT technology, becomes the prior option for the turbine impeller in-field inspection. This paper validated application of the PAUT on the straddle mount-type turbine disc inspection and determined the length and through-wall depth measurement via a series of experiments. The application of PAUT not only solves the conventional techniques limitation, but also improves the examinations efficiency, reliability and accuracy.