In order to investigate the mechanism and regular pattern of metal magnetic memory (MMM) signal, from the angle of electron spin, the magnetomechanical model of MMM is set up, and the relationship between stress concentration state and self magnetic flux leakage (SMFL) signal is calculated by the plane wave and pseudo-potential method based on the density functional theory. The research results show that the fundamental reason for SMFL is lattice distortion induced by loads, and the theoretical calculations are in very good agreement with the experimental observations. The present work is helpful for testing the mechanism of MMM.