Abstract: High quality alloy steel 40Cr is widely used in mechanical manufacturing industry and is selected for the high-cycle fatigue experiments in the paper. The relationship between the characteristic value of magnetic signals during the process of fatigue testing and the stress concentration position and the degree of stress concentration has been researched. The normal component and the tangential component are together detected. The method of Lissajous figure is used to draw two-dimensional curve, the relationship between area of Lissajous figure and the fatigue damage state of the specimen is discussed. It turns out that the mutation characteristics of differential gradient value can be used to accurately determine the stress concentration area caused by fatigue loading; very big change appears in magnetic signals under the beginning of the loading condition, while with the increase of fatigue cycles, the magnetic signal changes slowly. When the crack propagation stage in the specimen is aroused, magnetic signals increase significantly; and there is a good corresponding relationship between area of Lissajous figure and the fatigue damage state of the specimen. It is expected to provide test analysis basis for the quantitative analysis of two-dimensional detection of magnetic memory effect.