Abstract: The detecting and identifying of the seabed cable is becoming an important task to the detecting of the underwater canal.The feature of the magnetic abnormity which the cable produces can be applied to analyze and detect the exist of the seabed cable.The magnetic field model has been given in this paper,and the consistency of the magnetic abnormity distribution between the simulation of the model and the calculation from the observed data has testified the validity of the model.The conclusion is that the bental cable can be effectively detected and identified with reasonable detecting method.