A system of underground power cable path detection based on electromagnetic method is proposed, the system aim at the test site containing both running and non- running state of the cable, measure the three components of the magnetic field by three-axis high sensitivity magnetoresistive sensors above the ground , use pre-processing circuit to eliminate interference , then calculate the specific location of underground cables and the path toward by the magnetic field detection model, complete the running and non-running cables’ intelligent path detection.Matlab and Multisim simulation verify the feasibility of the magnetic field detection model and pre-circuit, respectively, indicating that the system of underground power cable path intelligent detection has good practicality.