The invention relates to a punching device for bridge plate production line. The punching device is characterized in that the punching device consisting of a square frame body, an II# upper connecting plate, a core plate, an inserting plate, a cylinder, a stripper plate, a cavity plate, a cavity bottom plate and a liner plate is installed in a transition bracket between the upper operating platform and the lower operating platform of a press, and a lower plate in the square frame body is arranged on the liner plate; the bottom surface of an I# upper connecting plate is connected with the II# upper connecting plate, and the core plate of a core die set is arranged on the bottom surface of the II# upper connecting plate; a pressing plate, the stripper plate and the cavity plate are installed on the bottom surface of the core plate in sequence; the inserting plate driven through the cylinder is installed in the core plate between core plate and the II# upper connecting plate. The punching device has the advantages that the design is reasonable, the structure is compact, not only punching and flanging can be simultaneously realized, but also the punched hole has accurate position, the production efficiency is high, the product quality is good, the labor intensity is low, the operation is safe, and the use is very convenient.