In the process of long-term power information transmission of submarine cables，sudden accidents such as damage and failure often occur. By studying the magnetic abnormal disturbance signals generated by submarine cables in geomagnetic background，the trajectory and buried depth of submarine cables can be determined，and the submarine cables can be quickly located in the area after the sudden situation，and the submarine cables can be repaired in time. The magnetic field model of the submarine cable is established based on the finite element simulation of microelement magnetic dipole，and the influence of detection distance（DCPA），cable length （L）and background magnetic field on the magnetic anomaly characteristics of the submarine cable is explored. It can be seen from the study that when DCPA <L，3L >DCPA >L，DCPA >3L，the attenuation index is about –2，–2.8，–3 respectively. When DCPA is fixed，the cable magnetic anomaly tends to be stable with the increase of the cable length to a certain extent，and the signal distorts. The change of the background magnetic field component may not only change the strength of magnetic anomaly signal of the submarine cable，but also change the signal waveform characteristics.
