In order to investigate the approach to characterize the damage behavior of ferromagnetic material components with flaw by metal magnetic memory testing, a sheet specimen with a precut notch of Q235 steel was chosen to measure the self-emitting magnetic signals on its surface during tensile test. The results showed that an abnormal magnetic signal appeared at the position of the precut notch after early loading and then transformed gradually to a clear magnetic abnormal peak with the tensile load increasing, which implied that the variations of self-emitting signals can reflect the influence of applied load on the specimen dynamically. The above-mentioned phenomenon was discussed from the point of view of magnetomechanical effect.