A parallel spreading scraping plough for longitudinal joints is mounted on the outer side of a front baffle plate of an asphalt spreader and comprises a plough share plate, a plough share frame, a suspension arm and a mounting support. The mounting support horizontally welded on the outer side of the front baffle plate of the spreader is connected with the suspension arm in a fastened manner by a fastening bolt, the suspension arm is perpendicular to the mounting support, the lower end of the suspension arm is fixedly connected with the plough share frame, one surface of the plough share frame is connected with the suspension arm, an oblique surface of the plough share frame is connected with the upper portion of the plough share plate, an oblique included angle is formed between the plate surface of the plough share plate and the plane with the suspension arm, and an oblique included angle is also formed between the lower end of the plough share plate and a ground surface. By mounting the plough share plate on the outer side of the front baffle plate of the asphalt spreader, a front spreader performs ploughing and spreading for joints simultaneously, when a rear spreader performs spreading, a ploughed portion of concrete is mixed with and heated by new high-temperature asphalt concrete, the joints are filled by the new concrete, and the parallel spreading scraping plough improves operation efficiency of the spreaders, guarantees construction quality, avoids cold joints on a pavement, and prolongs the service life of a road.