A ferromagnetic material that has undergone a saturation state can be treated as a magnet material. Machinery and equipment should be used to test the magnetic flux density around the electromagnetic coil to be above 80% of the magnetic flux density required for magnetization of the steel tube in the saturated state. Therefore, the steel pipe flaw detector machine and equipment should be selected according to the material and specifications of the steel pipe before flaw detection. The selection of magnetization current is generally carried out according to the comparison of specimens. Theoretically speaking, the magnetic flux density needed to achieve saturation magnetization of the tested steel pipe should be calculated first before selection, and then the magnetization current should be adjusted according to the provisions. This kind of method should be carried out complex calculation. In the concrete pipe flaw detector machines in practical operation, can choose simple adjustment methods multi-frequency eddy current flaw detector, namely in the back and forth according to the comparison specimens, eddy current flaw detection system with widening of magnetizing current and observe the steel pipe flaw detector machine equipment machinery and equipment display information noise data signals and artificial defect data transformation. When the noise data signal is the least and the artificial defect data signal is large, the magnetization current is the basic fit.