The invention relates to a metro double-column elevated station steel reinforced concrete transformation structure reinforcing bar and a construction method thereof. A transformation structure needs to be arranged on a metro elevated station because of the limit of road conditions, and an ordinary steel reinforced concrete transformation structure can not provide good bearing performances and earthquake-resistant performances. The metro double-column elevated station steel reinforced concrete transformation structure reinforcing bar comprises a reinforcing bar column section, a short beam of the reinforcing bar column section, reinforcing bar cantilever beam sections on two sides, and a reinforcing bar middle beam section in the middle, wherein the short beam is fixed together with the reinforcing bar cantilever beam sections and the reinforcing bar middle beam section by virtue of a reinforcing bar splitting plate and a high-strength bolt; a transition section with variable cross sections is respectively arranged at the lower part of the reinforcing bar column section and the end part of each reinforcing bar cantilever beam section; a column reinforcing steel bar connecting plate and a beam reinforcing steel bar connecting sleeve are arranged on a beam-column joint of the reinforcing bar column section; a column supporting joint column rib through hole reinforcement plate and a column supporting joint reinforcing bar beam section stiffening plate are arranged on a beam body at an underpinned column position. The reinforcing bar construction transformation structure disclosed by the invention is high in anti-bending and shear bearing capacity of components and small in deformation, can be used for improving the earthquake-resistance performances, and has wide application values in the metro double-column elevated stations.