The invention discloses an intelligent multifunctional cable line fault online monitoring system which comprises multiple fault detectors, a centralized processor, a communication interchanger and a monitoring system server. 2.4 G wireless communication modules, single-chip microcomputer control units, current sensors and lamplight alarm modules are arranged in the fault detectors. The centralized processor is connected with the monitoring system server through the communication interchanger, receives sampling data of the fault detector A, the fault detector B and the fault detector C, conducts preliminary fault information calculation and sends the processed and analyzed data to the communication interchanger, and the communication interchanger decodes fault information and uploads the decoded fault information to the monitoring system server. According to the intelligent multifunctional cable line fault online monitoring system, short-circuit, grounding, overload, broken-line, power-off, three-phase unbalance and stealing fault conditions and the like on a line can be comprehensively monitored and fault judgments are made rapidly and accurately.