Abstract: The excessive defects in aerospace aluminum alloy forgings were found during the processing in ultrasonic A-scan inspection. Qualitative analysis of defects was performed by means of ultrasonic phased array inspection, industrial computed tomography, penetrant testing, metallographic analysis and so on. The results showed that the cause for disqualified forgings was inclusion defects in the aluminum alloy bar, and this conclusion would provide certain reference basis for subsequent raw materials procurement and quality control.