The utility model provides an anti-falling device for a box girder, which is simple and convenient to operate. The box girder anti-falling device comprises a plate body with holes (1) and a limiting convex body, wherein the limiting convex body is connected on the plate body with holes (1). The limiting convex body comprises two flat plates (3) and a connecting piece (4) connected between the two flat plates; the two flat plates (3) are parallel with each other; and the two flat plates (3) are perpendicular to the plate body with holes (1). The device can be used for being connected and fixed between a box girder and a pier during the process of box girder anti-falling girder erecting, and prevent the danger of the falling off of the box girder caused by accidental vibration.