In order to avoid the frequent occurrence of cable cutting accidents in urban construction, the cable path should be located scientifically and reasonably. Taking three core cable as the research object, locating characteristic point and locating characteristic value K are introduced as the judgment basis of magnetic induction intensity above the cable, and the cable laying path is determined by the distribution characteristics of magnetic field around the cable. Then, the factors affecting the change of magnetic field around the detection points?wire core position, cable buried depth, laying spacing and different paths are analyzed by using this criterion. Simulation results show that the value of K can reflect the change of magnetic field environment around the cable well. The characteristic points appear near the top of the cable. Finally, the accuracy and feasibility of the criterion are verified by finite element and experiments. The principle of the proposed method is simple and portable, which provides an important reference for realizing intelligent and modern cable path positioning.