Aiming at the disadvantages of high cost and difficult operation of the laser radar wire safety distance detection scheme based on helicopter, this paper proposes a camera-based multi-rotor UAV monocular sequence image power line security distance detection method. The method is based on the GPS-assisted aerial triangulation in the photogrammetry and the intersection of the space front, and establishes the three-dimensional model of the ground object under the conductor to be inspected, and uses the human-computer interaction method to generate the sag model of the wire, and then the distance between the wire and the ground object. Calculate, according to the set threshold to determine whether the spacing meets the specifications. In particular, this paper proposes a method for accurately calibrating the relative position of GPS and camera, and realizes the conversion of GPS coordinates and camera coordinates. At the end of the paper, the detection method proposed in this paper is verified by comparison experiments. The experimental results show that the detection method can effectively detect the safe distance of the tested wires.