A mechanical device of a skylight sealing strip finish cutting machine comprises a mechanical device body and sealing strip positioning devices. The sealing strip positioning devices are arranged on the two sides of the mechanical device body. A protective shell is detachably arranged outside the mechanical device body which is internally provided with a knife rest turnover mechanism, a blade cutting mechanism, a blade fixing mechanism, a motor, a discharge slide plate and a collection frame. The motor is arranged above the blade cutting mechanism. The blade fixing mechanism is arranged under the blade cutting mechanism. The knife rest turnover mechanism is arranged behind the blade cutting mechanism and the blade fixing mechanism. The discharge slide plate is arranged in front of the blade fixing mechanism. The collection frame is arranged under the discharge slide plate. The knife rest turnover mechanism comprises guide rails, a cylinder, a tension rod and a fixing plate, wherein the guide rails are arc-shaped guide rails. The mechanical device has the advantages that a beveling blade is positioned through the arc-shaped guide rails, and the product machining precision is improved; and a beveling task is completed through cooperation of upper and lower blades, and the product production efficiency and the product quality stability are improved.