Based on Xuchang 110 kV Fu-Ge line reconstruction project, Xuchang high-voltage power transmission line online video monitoring system is designed to facilitate the study of the application of such system in Xuchang power grid. This paper introduces the current situation of high voltage power line monitoring and studies the technology of real-time monitoring of transmission line. In the light of actual needs of the development of Xuchang power grid, this paper adopts the latest EPON optical transmission technology, the high voltage induction power supply and other advanced technologies to set up an on-line video monitoring system for Xuchang power transmission line. The system overcomes the disadvantages of the traditional wireless transmission and solar power technology. The testing verifies the system has obvious advantages compared to other video monitoring systems, such as high efficiency of image transmission, reliable and stable power supply system, and good application prospects.