Abstract: In order to clearly highlight the boundary information of geological bodies in the geomagnetic field and the spatial distribution characteristics of fault structures, make the magnetic anomaly image clear and intuitive, and facilitate the understanding of the anomaly characteristics of the geomagnetic field from different perspectives, and provide reasonable geological explanations, a magnetic anomaly boundary identification method based on the inverse tangent function of the magnetic gradient tensor was proposed. This method highlighted the morphological characteristics and spatial location information of geological bodies and fault structures by calculating the inverse tangent angle of the ratio of the vertical derivative of the vertical component of the magnetic gradient tensor to the horizontal derivative of the horizontal component. It also identified the boundaries of geological bodies and the spatial distribution characteristics of fault structures based on the position of the maximum value of the inverse tangent angle. The comparison results of the model test show that this method can accurately identify the boundary positions of geological bodies and has the characteristics of high resolution. It is also unaffected by the burial depth and occurrence of the geological bodies, with strong resistance to high-frequency noise interference and little influence from oblique magnetization. It can highlight the occurrence and other information of the geological bodies and is of reference significance for identifying the boundaries of geological bodies and determining the orientation of geological structures.