The invention discloses a theft-proof early warning system for cables, which can effectively judge cable faults. The system comprises master equipment and slave equipment; the master equipment comprises a master processor module, and a GPRS (General Packet Radio Service) remote communication module, a high-frequency carrier transceiving module I, an audio carrier transmitting module, a CT power taking module I and an electric field measuring module I connected with the master processor module respectively; the slave equipment comprises a slave processor module, and a high-frequency carrier transceiving module II, an audio carrier receiving module, a CT power taking module II and an electric field measuring module II connected with the slave processor module respectively; the high-frequency carrier transceiving module I and the high-frequency carrier transceiving module II are separately connected to two ends of a cable inner conductor; the audio carrier transmitting module and the audio carrier receiving module are separately connected to two ends of a cable shielding layer; the CT power taking module I and the CT power taking module II are separately connected to the two ends of the cable inner conductor; and the electric field measuring module I and the electric field measuring module II are separately connected to the two ends of the cable inner conductor.