The invention discloses a pipeline defect detection method based on electromagnetic ultrasonic longitudinal guided
waves. The method comprises the following steps: arranging a plurality of annular magnets coaxial with a pipeline, so as to generate a radial static
magnetic field on the surface of the pipeline; coaxially sleeving two sides of each annular
magnet array with solenoid coils, so as to generate circumferential inducing vortex in the to-be-detected pipeline; and stimulating longitudinal-mode guided
waves under the combined action of the circumferential inducing vortex and the radial static
magnetic field, wherein when encountering a defect, the longitudinal-mode guided
waves are reflected, and reflection echoes cause change of sensing
voltage of a sensing coil when passing through a sensing coil, so as to judge that whether the defect exists in the pipeline or not. The invention further discloses a detection device and a sensor for detecting the pipeline by virtue of the device and the method. According to the method, the radial magnetic fields at the edges of the
magnet arrays are adequately utilized, and the uniform radial
magnetic field does not need to be generated, so that the complexity of the sensor is reduced; meanwhile, a single longitudinal-mode guided wave
signal can be obtained, so that the defect
signal analysis difficulty is reduced, and the detection process is rapid and efficient.