Abstract: Submarine hybrid line laying is complex, when there is a fault on the line, it is difficult to locate the exact location of the fault. Therefore, fast and accurate fault location is the key point to speed up the repair of transmission lines and reduce the outage time. Based on the structure analysis and fault analysis of the submarine hybrid line, an integrated fault location system for the hybrid line is proposed. The system is composed of line protection relays on the ends of the hybrid line and section positioning devices on the ends of the cable. Three phase currents on both sides of the cable are collected by using the flexible optical current transformer which suits to be installed on the joint points. The differential current of the cable section is calculated through optical fiber, then the fault section is determined. When the fault is in the cable, the reclosing function on both sides of the line is blocked immediately. In addition, the line protection relays on both sides integrate the traveling wave fault locating function. With receiving the fault’s section signal, traveling wave fault location can accurately locate the fault point. With lots of simulation tests, it can be proved that the proposed integrated system can realize the hybrid line precise fault location of the hybrid line. It can greatly improve the power supply reliability of the hybrid lines.