The power supply reliability of the urban distribution networks is being challenged by cable faults. Owing to the complex factors, such as system neutral, fault condition, and DG integration, it is difficult to detect and locate the fault cable. In this paper, the equivalent circuit model of the distribution cable is firstly created by considering the multi-conductor couplings. The mathematical relation of the amplitude differences between zero-sequence currents and those flowing in cable sheaths and armors at the local end of the healthy and fault cables are then derived in theory. Finally, according to the network topology and measurement locations, a novel method for identifying the fault cable section is proposed by using the defined space-measurement matrix. The simulation model of a real urban distribution network is established in PSCAD/EMTDC. The effectiveness and robustness of the proposed method are validated. The results demonstrate that the method is barely affected by the neutral grounding mode, fault initial condition, and distributed generation (DG) penetration level.