Abstract: Unmanned aerial vehicle (UAV) is the most ideal tool for transmission line inspection. By being mounted with the optical cameras, the infrared imaging technology, the lidar and other devices, a UAV has become an indispensable measure for overhead transmission lines inspection, checking the wires, insulators, electric power fittings and other power transmission equipment. This paper first introduces the application status of the mounted UAV for transmission line inspection. The working pattern of the mounted UAV for transmission line inspection is systematically discussed. In addition, some key technologies of the mounted UAV for transmission line inspection are emphatically reviewed, such as its endurance, the safe distance for inspection, its anti-electromagnetic interference design, and the like. Finally, the development trend of the mounted UAVs for transmission line inspection is concluded, aiming to provide some useful references for related researches.