The invention discloses a power transmission line inspection system based on a fixed-wing unmanned aerial vehicle. The power transmission line inspection system based on the fixed-wing unmanned aerial vehicle comprises a ground station and a fixed-wing unmanned aerial vehicle, wherein the ground station comprises a ground control system, an image receiving system, and a data processing system, the fixed-wing unmanned aerial vehicle comprises an unmanned aerial vehicle body, a remote sensing monitoring device, a real-time detection device, an image transmission system, an instruction receiving system, a power system, and a flying control system. The remote sensing monitoring device is used for collecting image information in an area of a power transmission line at a fixed time or a fixed distance or a fixed spot, the real-time detection device is used for collecting information in the area of the power transmission line in real time, and the remote sensing monitoring device and the real-time detection device are arranged on the unmanned aerial vehicle body in a front-and-back adjacent and direct-to-ground mode. The power transmission line inspection system based on the fixed-wing unmanned aerial vehicle is capable of conducting periodical or emergent macroscopic inspections on the power transmission line and accessory equipment of the power transmission line, so that labor intensity of manual power transmission line inspection work is greatly reduced, and power transmission line inspection efficiency is improved.