Aimed at the problem that the defects of surface and subsurface are very hard to detect on the ferromagnetic components, the pulsed electromagnetic testing model is established. The physical mechanism of a method composed of the pulsed magnetic flux leakage (PMFL) and pulsed magnetic reluctance (PMR) under the surface and subsurface defect is revealed. Both the simulation and experimental results indicate that the magnetic flux leakage exists in the surface defect of ferromagnetic, but the subsurface defect detecting signal is the change of the pulsed magnetic resistance. For the different depth of the surface defects, the pulse leakage magnetic response signal picked by GMR sensor is better linearity and higher sensitivity; For the different subsurface defects of ferromagnetic components, the relationship between the characteristic value of the pulse magnetoresistance response and the depth of the defects is similar to the linear growth relationship, and the discrimination degree is larger and the detection performance is better.