Abstract: The probability of detection (POD) of defects are fundamental data for the damage tolerance design and serving life prediction. In this work, the POD of ultrasonic inspection was investigated for inclusions within powder metallurgical turbine disks, which are vital rotating parts of aeroengines. Artificial FBH samples were fabricated with different diameters and buried depths, as mock-up for non-metallic inclusions in disks. The zoned ultrasonic immersion inspection procedures by 6 sets of ultrasonic probes were used for the inspection of the above-mentioned samples, and the statistical data of POD for different artificial defects were acquired, based on which a POD curve of probability versus defects sizes were drawn. The results tell that for this specific inspection procedure, the equivalent detectable defect size at a probability of 90% is 0.167mm, giving 95% confident level.