Abstract: The grinding undercut of 1117-600-Э-M3 valve rods had broken twice during the operation period in a NPP. In order to prevent the breaking happening again, it is necessary to carry out a complete inspection for the same type valve. The valve is very big, and the workload is also very heavy for the strip inspection. The technique of ultrasonic phased array inspection for the structure features of valve was developed, and an inspection was carried out during the outage. The inspection results showed that the ultrasonic phased array inspection technique can make an efficient inspection for the broken parts of valves and decrease the dismounting work at the same time.