A multifunctional sensor for high-voltage cable monitoring relates to a sensor. At present, the sensors of the existing monitoring device need to be powered by an external power supply, and the device comprises many supporting parts and is too large and inconvenient to operate and use. The multifunctional sensor comprises a wideband current sensor which is used for detecting partial discharge signals and capacitive current, a bus current collector which is used for acquiring the current of a bus, a signal processing device for signal processing which is connected with the wideband current sensor and processes the signals output by the wideband current sensor to get high-frequency pulse signals and capacitive current signals, and a cable shielding layer loop current energy acquiring device which is used for acquiring electric energy from the bus and is connected with the signal processing device. According to the technical scheme, power cable metal shielding layer loop current energy acquisition is adopted, no additional power supply is needed, and certain resources are saved. The sensor is more independent, convenient and quick in use, and is free from the bondage of an external power supply.