The milling machine is characterized by the use of mobile gantry rack and pinion feed, the platform is unlimited by machine's length and can be extended trip (which can be 36 meters or longer). Longmen on both sides of the rack and pinion drive the adoption of a bilateral motor drive from the top of the goal, Longmen on both sides of the rack and pinion drive the adoption of a bilateral motor drive from the top of the goal, so that the design on both sides of the Longmen synchronization has been assured, mobile gantry adopts four rail rolling in a straight line, so that the machine moves a light rapidly and live longer, the beams adopts fixed-beam and moving beams, the span of Longmencan be achieved 6 meters without restriction.