The invention discloses an unmanned plane based live-line test apparatus for hydrophobicity of composite insulator of power transmission line. The Unmanned plane based live-line test apparatus for hydrophobicity of composite insulator of power transmission line comprises an unmanned plane, wherein, the unmanned plane is provided with a wireless remote controller, a water spraying apparatus and an image acquisition and transmission apparatus, the water spraying apparatus comprises a water tank, a water pump and a nozzle, wherein, the water pump and the water tank are connected with each other, and the water pump is connected with the nozzle by a water spraying pipe; the image acquisition and transmission apparatus comprises a pick-up head and an image transmitter, and the pick-up head and the image transmitter are connected with each other; the wireless remote controller comprises a wireless remote control receiver, a wireless communication module, a nozzle remote control mechanism, a pick-up head remote control mechanism and a water pump starter, and the wireless remote control receiver is respectively connected with the nozzle remote control mechanism, the pick-up head remote control mechanism and the water pump starter; the nozzle remote control mechanism is connected with the nozzle, the pick-up head remote control mechanism is connected with the pick-up head, and the water pump starter is connected with the water pump. The apparatus provided by the invention can effectively eliminate hidden troubles and is convenient and easy to operate, thereby reducing labor intensity of personnel to a large degree and guarantying personal safety.