Abstract: Due to its unique advantages,power cable has been widely adopted by coal mine power supply,but its fault is also increased. Since the laying position of most cable is more subtle,the detection of fault point has become more difficult. This paper which is based on zero sequence DC theory established a cable distance equivalent circuit model based on the DC component,with which could eliminate the need for complex AC and its interference analysis and simplify the analysis process greatly. In this paper,a multi branch cable model is built by Sim Power Systems in MATLAB and the simulation dates are used in training neural network. Finally,verified the feasibility and validity of the measurement scheme by the simulation results.