The invention discloses a detection device for detecting the stress of a pantograph on an overhead line system. The detection device comprises a camera, a white background board, a background board flash lamp, a trigger sensor and a pull force detection device; and the camera and the background board are installed on the same horizontal plane with the overhead line system; and the trigger sensor is installed below the camera. When pulling upwards the overhead line system, the pull force detection device is in linkage with the camera, so that photographing can be performed, and therefore, a displacement and pull force corresponding diagram can be obtained; the pull force detection device is removed, only the camera, the background board, the background board flash lamp and the trigger sensor are left on a site. During detection, when a pantograph at the top of a train passes the trigger sensor, the camera shoots a set of photos of the raised state of the overhead line system during thecontact of the overhead line system with the pantograph; and an actual pull force value is obtained through the comparison of the pixel value of the photos with the displacement and pull force corresponding diagram. The detection device of the method is simple and quick, does not occupy a space, has high safety and high reliability, and can better serve pantograph-overhead line system safe contactin the railway industry.