Abstract: The technology of magnetostrictive guided waves has been extensively applied in pipeline detection because of the excellent advantages, high efficiency and comprehensive detection of cross section, for example. However, the effectiveness of guided wave detection technique is affected by various factors, such as elbow, bracket bearing and welds, which might lead to detection failure. In this paper, based on corroded lamination defects which are discovered in the experiments, the attenuation effect of magnetostrictive guided waves caused is investigated with careful anatomy. The results show that the laminated corrosion defect has severe impact on the signals loss and it is also difficult to be determined by other non-destructive testing methods also.