The invention discloses a bridge expansion device easy to replace a waterproof sealing belt. The bridge expansion device comprises two mutually symmetrical anchoring sectional materials arranged on and fixed to adjacent bridge body end parts through anchoring ribs, wherein each anchoring sectional material is provided with a large cavity and a small cavity; a waterproof sealing belt is connected between the two anchoring sectional materials and comprises two connecting lug belts and an expansion body for connecting the two connecting lug belts; the two connecting lug belts are respectively arranged in the small cavities of the anchoring sectional materials at two sides. According to the bridge expansion device easy to replace the waterproof sealing belt provided by the invention, a damaged waterproof sealing belt can be conveniently and quickly taken out, and a new waterproof sealing belt is replaced and installed conveniently, so that the service life of the bridge expansion device is prolonged; the anchoring sectional materials adopt aluminum alloy, metal, engineering plastics, resin or polyurethane materials, so that the cost of an existing expansion device is reduced, and the anti-corrosion capability of the expansion device is further improved.