Abstract: This paper focuses on the difficulty of eddy current testing of the expansion zone, and studies the rotary eddy current testing process. Suitable technological parameters were determined by testing of sample and heat transfer tube plate. The results of expansion tube anatomy and penetration testing show that the scheme is effective. For the application of the method, thousands of heat tube expansion zone were tested, and the reliability of the rotary vortex current testing process was verified by water pressure testing and leakage testing.