The invention discloses a hydraulic concrete exterior steel plate reinforcing structure. The hydraulic concrete exterior steel plate reinforcing structure comprises a reinforcing steel plate attached to the surface of hydraulic concrete to be reinforced, a plurality of fastening bolt assemblies arranged on the reinforcing steel plate at intervals and used for fastening the reinforcing steel plate to the surface of the hydraulic concrete to be reinforced, a welding rod welded between the periphery of the reinforcing steel plate and the surface of the hydraulic concrete to be reinforced in a sealed mode, and pouring glue filling the gap formed by the reinforcing steel plate and the hydraulic concrete to be reinforced. The invention further discloses a construction method of the reinforcing structure. The hydraulic concrete exterior steel plate reinforcing structure has the beneficial effect of effectively improving the strength and the integral rigidity of original hydraulic concrete.