The invention discloses a double-flat-arm derrick construction process displacement monitoring method based on computer vision, and the method comprises the steps: installing a ground camera near a tower body of a power transmission tower, and guaranteeing that the tower body of the power transmission tower is in a video image of the ground camera; loading trolleys of flat arms on the two sides of the holding pole are each provided with a flat arm camera, and it is ensured that a power transmission tower body and a holding pole tower body are located in video pictures of the flat arm cameras; through the steps of selecting a displacement monitoring point, pasting a marker, calibrating a camera, calculating the displacement of the marker at all moments, and obtaining a displacement time travel curve, power transmission tower settlement displacement monitoring, holding pole tower body displacement monitoring and holding pole flat arm displacement monitoring are respectively realized. According to the invention, the overall settlement displacement of the power transmission tower body in the construction process can be monitored, and the displacement of the tower body of the holding pole and the displacement of the horizontal arm of the holding pole under the action of wind load in the hoisting process can be monitored.