The magnetic memory method can effectively determine the stress damage areas of the ferromagnetic metal components. However, the formation mechanism and complicated influenced factors of the spontaneous magnetic flux leakage signal make it hard to quantitatively analyze the magnetic memory signals under different stress concentration, and limit the practical applications. According to electron spin, the electronic exchange model of the sd orbit is established, the changing rules of the electronic spin of density, the atomic magnetic moment and the crystal lattice size nearby the field of the crystal are calculated. Furthermore, the relationship between the magnetic memory signals and the degree of stress concentration is quantitatively analyzed. Results show that the magnetic memory signal varies linearly with the stress. Before the yielding stress appearing, the magnetic memory effect is determined by the electronic spin interactions of the d orbit, and the repeatability of the relationship between the magnetic memory signals and the stress is good. After the yielding stress appearing, the electronic spin interactions enhance, the electronic spin interactions of the d orbit weaken, the electronic action of the s orbit enhances, the amplitude of variation of the magnetic memory signal decreases, and the whole magnetic memory effect weakens.