This project intends to study the new SSTDR detection technology applicable to the characteristics of low-voltage distribution network by analyzing the existing online fault detection technology of distribution network, combining the importance of distribution network, the complexity of scene and the low resistance of large cross-section. A new technology of subsection fault detection and location for multi-branch power networks is studied. This project collects the actual data of transmission lines in the high-voltage transmission system to locate the start-up fault in real time. Multiple segment ends are located synchronously by a time-domain echo generator with spread spectrum. This solves the problem of multiple branch delay in T-shaped connection and branch in HV transmission system. By using PSCADEMTP software, the fault locations under different fault types and different grounding modes are analyzed. Thus, the correctness and adaptive ability of the algorithm are verified.