Abstract: As a new non-destructive detection mean, ultrasonic guided-wave technology is more and more widely used in pipeline inspection. The detection devices of ultrasonic guided waves and dispersive characteristics are introduced briefly. Based on the non-dispersion of T(0,1) mode, the reflected signals are analyzed with dynamic frequency in low frequency range(below 70 kHz) . The inspecting results show that the method can clearly identify the feature signals of pipeline and find out the accurate location of corrosion defect. Because of the superposition of reflected signals, the corrosion defects which are in the same section of asymmetric characteristics in pipeline are however difficult to distinguish.