The invention discloses an electric transmission line insulator online fault locating system based on a Zigbee, and belongs to the technical field of electric power transmission. The electric transmission line insulator online fault locating system comprises a Zigbee master monitoring station and multiple Zigbee measuring point devices, and the Zigbee measuring point devices are mounted on metal components of insulators which need to be detected and are distributed on pole towers. Peer-to-peer network topology structures are adopted in a Zigbee network formed by the master station and the Zigbee measuring point devices and a Zigbee network formed by the Zigbee measuring point devices. The master station comprises a master station Zigbee module and a microcomputer device, and each measuring point device comprises an annular magnetic core, a first Hall current sensor, a second Hall current sensor, a differential amplification module, a numerical control partial pressure module, a control switch trigger module and a measuring point Zigbee module. The master station is arranged in a power substation watched by people, the first Hall current sensors and the second Hall current sensors of the measuring point devices are arranged at the positions of the ring diameters of the annular magnetic cores, the annular magnetic cores are of a structure capable of being opened and closed, and the metal components of the insulators are sleeved with the annular magnetic cores.