To study the relationship between early damage of ferromagnetic materials and metal magnetic memory signals，the relation between the permeability of ferromagnetic material and applied load is analyzed by combining the force magnetic coupling model with the magnetic dipole model.The static magnetic and static magnetic modules of ANSYS Workbench finite element simulation software are used to simulate the force magnetic coupling of 45 steel specimens under the magnetic field.The variation law of leakage magnetic field strength and the distribution law of vertical component B （y） gradient value K are obtained under different tensile stress.The results show that the magnetic memory signal increases with the stress in the stress concentration zone.And the results provide a reference basis for the metal magnetic memory testing technology in the detection of the stress concentration area of ferromagnetic materials.