Abstract: In the inspection of tubes in service, the most common method is the electromagnetic method, which however can not measure the defect and corrosion precisely. This paper introduced a new nondestructive testing (NDT) technology: the inner rotating ultrasonic inspection system(IRIS). Using this new technology, we can detect the inner defect and internal or external corrosion omni directionally, which its precision being almost the same as common ultrasonic test method. The proposed method can satisfy the requirement of inspection and overhauling. It also enhances the accuracy and reliability in the inspection of heat exchanger tubes.