Abstract: The exchange tube of steam generator is the weak point of reactor's primary circuit. Usually the degradation of PWR nuclear power plant steam generator is mainly caused by corrosion and mechanical wear which include intergranular corrosion, stress corrosion cracking, reduction, dent, mechanical wear, fatigue and etc. In order to detect the defects of heat transfer tubes with higher efficiency and reliability, this article aims to analyze their characteristics. A series of experiments were carried out for the comparison of the defect recognition and detection ability of these two types of probes. The ability of eddy current testing with these two kinds of probes was determined as well.