The utility model discloses an adjustable flatcar is used in bridge construction, including two bottom plates, two one side that the bottom plate is relative is all articulated mutually through the long tube, two the ring piece has all been cup jointed at the both ends of long tube, the ring piece rotates with the long tube to be connected, the one end that the ring piece is close the bottom plate is equipped with first gear, first gear and pulley area are rotated and are connected adjacent two the pulley area is rotated and is connected, first gear is connected with the second gear through pulley area rotation, the second gear cup joints in the pivot, pivot and bottom plate rotate to be connected. The utility model discloses an in the use, for the article that transports that adapts to different specifications, make the flatcar tensile, satisfy more goods demands of transporting, in that the share -car is idle when parking, can remove limiting plate to original place, contract the expansion plate to the inslot of bottom plate, reduced occupation of land space area, the work of the giving constructor efficient flatcar device that facilitates.