The invention discloses a scanning device for rail seam inspection. Two ends of a rectangular support frame (1) are provided with 'n' shaped fixing pins (7); two ends of a slide rail (2) are fixed on The invention discloses a scanning device for rail seam inspection. Two ends of a rectangular support frame (1) are provided with 'n' shaped fixing pins (7); two ends of a slide rail (2) are fixed ontwo ends of the rectangular support frame (1); a first probe case fixed mount (3), a second probe case fixed mount (4) and a third probe case fixed mount (5) are arranged on the slide rail (2) and cantwo ends of the rectangular support frame (1); a first probe case fixed mount (3), a second probe case fixed mount (4) and a third probe case fixed mount (5) are arranged on the slide rail (2) and canslide freely along the slide rail (2); two ends of the rectangular support frame (1) are provided with a rotating shaft (11) of an inhaul cable respectively; and the inhaul cable (6) is winded on two slide freely along the slide rail (2); two ends of the rectangular support frame (1) are provided with a rotating shaft (11) of an inhaul cable respectively; and the inhaul cable (6) is winded on two rotating shafts (11) of the inhaul cable along the direction of the slide rail. The scanning device has a simple structure and convenient operation, and adopts mechanical scanning to replace the priorotating shafts (11) of the inhaul cable along the direction of the slide rail. The scanning device has a simple structure and convenient operation, and adopts mechanical scanning to replace the prior manual inspection of seam inspection, thereby greatly improving the accuracy of rail inspection, and realizing inspections on a plurality of seams.r manual inspection of seam inspection, thereby greatly improving the accuracy of rail inspection, and realizing inspections on a plurality of seams.