The invention relates to a method of positioning a detector magnetic label in a buried steel pipeline. Two groups of three-component magnetometer probes vertical to axial direction of the pipeline make up a detection array, and a distance between probes is 1; the first probe is in a lateral position of the pipeline, and is used for measuring background magnetic fields generated by the steel pipeline and the ground; the second probe is in the center of an instrument, a buried pipeline is below the second probe, the three-component probe measures strength of magnetic induction in x, y and z three orthogonal directions generated the magnetic label and transferred to the ground in the background magnetic field; a detector moves steadily on the ground along a pipeline route, and calculates difference of three components of the two groups of probes; and the position and bury depth of the positioned magnetic label buried nearby the pipeline can be measured by using a magnetic positioning method. The method can be applied to a permanent magnetic label detection system for in-pipe inspection mileage calibration and elimination of magnetic field of the steel pipeline and ground magnetic background, thereby being widely used for detecting position and bury depth of a lost magnetic label.