In order to research the character signal of high load rotating bending fatigue before the fracture of specimens,the theoretical study was conducted based on magnetomechanical effect and magnetic field superposition,and the high load rotating bending fatigue experiment was carried out on 45#steel specimens with annular notch.The distribution variation of normal magnetic signals was analyzed.Theoretical analysis indicates that the magnetic signal distribution near the fatigue crack changes as the crack propagates.Experimental results show that,before and after the rapid crack propagation,the size order of signal near the crack changes. The detection effect is impacted by nominal stress,stress concentration factor,environmental magnetic field and sensor liftoff,then the corresponding strategies are put forward.So it is feasible to detect high load rotating bending fatigue damage using metal magnetic memory technique.