The invention discloses a large-span double-arch axis combined arch bridge, which comprises a main beam, a middle bridge pier serving as a middle fulcrum, two auxiliary bridge piers serving as two end fulcrums, an arch axis assembly and two upwards protruded arc arch axis bent beams, wherein the arch axis assembly is arranged on the middle bridge pier, two ends of the arch axis assembly are respectively butted with the inside ends of the two arch axis bent beams, the outside ends of the two arch axis bent beams are respectively arranged on the two auxiliary bridge piers, and the two arch axisbent beams are connected with the main beam through a plurality of stay ropes. The invention also discloses a construction method of the arch bridge. By adopting the double-arch axis method, the bending strength of the section of the arch bridge is greatly increased, the bending moment of the arch section at the middle fulcrum is reduced, the vertical displacement of the arch waist is low, and the deformation of the main beam is reduced, so that the whole bridge is stressed reasonably. By using the method, the construction cost can be effectively reduced, and the construction period is shortened.