Abstract: To address the issues of low efficiency and high risks associated with manual tower climbing during the outage maintenance of extra- and ultra-high voltage transmission lines, this study developed an unmanned aerial vehicle -mounted voltage detection device. This system enables fully automated, ground-controlled operation throughout the entire inspection process. It integrates technologies including advanced insulating materials, high-precision sensing, digital signal processing, wireless communication, and Internet of Things monitoring. This integration facilitates remote, non-contact, and intelligent diagnosis of the line"s potential status. Field applications demonstrate that the device reduces the operational time by 70%, cuts down the required personnel to two, and achieves a voltage verification accuracy rate of 100%. It significantly enhances both safety and operational efficiency, offering a novel solution for the intelligent maintenance of power grids.