The invention belongs to cold roll forming equipment and particularly relates to a device for preventing a longitudinal wary cambered surface generated by cold roll forming. The device is characterized in that a carrier roller device for supporting the bottom surface of processed workpirces is arranged on a stand corresponding to the position of an outlet end of a rolling port of each rolling mill in a forming section S, wherein the carrier roller device consists of a transverse plate, a swing arm, support seats, a swing arm shaft, a carrier roller, a carrier roller shaft, an adjusting bolt and a bracket; the adjusting bolt for adjusting the lifting height and transverse movement of the carrier roller is arranged on the bracket; the top end of the adjusting bolt is in contacted connection with the bottom surface of a carrier roller slot; the bottom end of the adjusting bolt penetrates through adjusting bolt hole and extends and exposes out of a top plate of the bracket; and a plurality of adjusting nut holes for adjusting the transverse positions, which are matched with the adjusting bolt, are arranged in a top plate surface of the bracket. The device disclosed by the invention is reasonable in design and compact in structure; according to the device, the defect of longitudinal wavy cambered surface is prevented and the rigidity and the strength of a box plate are enhanced; in addition, the device has the advantages of attractiveness in appearance, high production efficiency, higher convenience for operation and use and the like.