Abstract: In order to meet the needs of nuclear fuel assembly damage inspection, a complete inspection system suitable for ultrasonic inspection of fuel assembly damage has been developed. Based on the characteristics that the inner cavity of the fuel rod is filled with water after the fuel rod is damaged, the energy loss of the ultrasonic signal transmitted along the fuel rod cladding is detected to determine whether the fuel rod is damaged. The composition of the detection system was introducted, and a series of verification tests based on the special requirements of the detection environment were carried out, including ultrasonic signal test of calibration components and analog components, irradiation test, probe high temperature test and field verification. The test results show that the developed ultrasonic probe and inspection system can effectively identify intact calibration rods and damaged calibration rods. The inspection system has the ability to perform automatic ultrasonic inspection of damaged fuel assemblies.