Abstract: Aiming at the widely used GCr15 high-carbon chromium bearing rollers, a micro-crack magnetic flux leakage detection method was proposed. COMSOL finite element software was used to simulate and analyze the leakage magnetic field characteristics of roller micro-cracks, and the influence of magnetization parameters and crack size on the signal was studied. Tunneling magnetoresistance sensor (TMR) was used to pick up the signal. Since TMR is prone to over-range saturation under strong background magnetic field, a TMR magnetometry method with near-zero magnetic field regulation in the measuring point region was proposed. The offset detection probe with electromagnetic magnetization of the coil was designed, and the self-adaptive near-zero magnetic field environment of the measuring point area was established. The amplitude and signal-to-noise ratio of the detection signal before and after the probe offset were compared and analyzed through experiments, which showed that the performance of the probe was optimized.