The effects of mechanical stress on the magnetic characteristics of materials indicates it possible to quantitatively measure and evaluate stress via the testing of stress-induced magnetic component. At present, however, the stress-associated magnetic component is extracted from the inducting magnetic field, which is mingled with the environmental magnetic field and the residual magnetic field of the materials. Both factors are difficult to be isolated, leading to: 1) poor stress measuring precision and 2) misunderstanding of the mechanism between stress and the magnetic characteristics. In this article, the relationships between the stresses and the excitation magnetic fields of three materials are investigated, with a proposed method to extract the stress-induced component. The results show that: 1) the stress effect on the excitation magnetic field is evident, and a method to extract the stress-induced magnetic component is proposed and 2) the relationship between the stress and the stress-induced magnetic component is affected by the material’s permeability and conductivity. The findings and proposed methods are helpful to enrich the understanding of the magneto-mechanical effect and improve the stress measurement.