Flatness detection device for road construction

The invention discloses a flatness detection device for road construction, and relates to the technical field of road detection devices. Comprising a longitudinal rail, a transverse rail and a measuring device, the measuring device comprises two sliding blocks, a through hole is formed in the outer wall of each sliding block, and a movable groove is formed in the outer wall of the bottom of each sliding block. Measuring rulers are arranged on the outer walls of the two sliding blocks, measuring plates are arranged in the two sliding blocks in a sliding mode, connecting shafts are arranged on the outer walls of the measuring plates, the connecting shafts are inserted in the corresponding through holes in an up-down sliding mode, a comparison ruler is arranged on the outer wall of each measuring plate, and bidirectional pointers are fixedly arranged on the outer walls of the measuring rulers. When the sliding block moves forwards and encounters an uneven ground, one side of the measuring plate is high, the othe