Abstract: The influence of different location of metal pipeline corrosion on transient electromagnetic testing signal is studied. By making the experimental device, the corresponding test scheme is designed. The test results show that in the coverage of the sensor, the defect has a great influence on the amplitude of the detection signal on the circumference of the pipeline and the signal amplitude is minimum when the defect is under the straight line of the pipeline. The amplitude of the signal is maximum but will not exceed the signal amplitude without defect at the bottom of the pipeline. The value is basically not affected by the axial direction of the pipeline. At the same time, the mathematical relationship between the detection signal and the radial angle is also determined. It provides guidance and reference value for the optimization of transient electromagnetic probe and the accurate location of metal pipeline defects in pipeline inspection industry.