The invention discloses a reinforced concrete arch bridge and bridge deck slab reinforcing device, which structurally comprises bridge piers, arch rings, a bridge deck and reinforcing device bodies. The bridge deck is arranged above the arch rings; the bottoms of the arch rings are connected with the bridge piers; the reinforcing device bodies are mounted in the arch rings and are each composed ofa connecting plate, face plates, two supporting rods and jacking rods, wherein the two supporting rods are mutually symmetrical; the connecting plates are each in an arc shape, and the two ends of the connecting plates are upward and are embedded into the position between the arch rings and the bridge deck; and the bottoms of the connecting plates are exposed to the tops in the arch rings. The reinforced concrete arch bridge and bridge deck slab reinforcing device has the beneficial effects that through the design of the arc-shaped connecting plates, the connecting plates can be quickly embedded into steel bars at the two ends of cracks, the two ends communicate, concrete is filled, thus the connecting plates and the two ends of the cracks are integrated to bear force, and the thickness is increased, so that the force-bearing degree is increased; and the arc-shaped connecting plates can disperse the borne force, the vertical force-bearing degree is decreased, and then the overall strength of a bridge is improved through the face plates, so that the bridge is firmer.