The invention discloses a cable line fault intelligent on-line monitoring system, which comprises a monitoring front end, and is characterized in that the monitoring front end is provided with a monitoring system, and the monitoring system comprises a control module, an on-line monitoring module, a current detection module, a centralized processing module and a communication module; the monitoring rear end is provided with a monitoring station, the monitoring station is internally provided with a CPU, the CPU is the core control of the monitoring station, and the monitoring station is also internally provided with a signal receiving unit, a signal analysis unit, a signal processing unit, a signal sending unit and a signal alarm unit; and the monitoring terminal comprises a computer, a mobile phone and a tablet personal computer and is used for receiving the fault information of the cable line. Intelligent real-time online monitoring is carried out on the cable line through the monitoring front end, the monitoring rear end and the monitoring terminal, the technical principle of a traditional common fault detector is broken through, the application range is wider, and installation and use are reliable.