The invention relates to a railway bridge, in particular to an ultra-wide cross-sectional structure suitable for a through steel truss girder of a double-track railway. Comprises a steel truss beam, across beam for supporting the line and a transverse inclined bar, wherein the cross beam is located at the top of the steel truss beam, the transverse inclined bar is located below the cross beam, one end of the transverse inclined bar is connected with the middle of the cross beam, the other end of the transverse inclined bar is connected with the steel truss beam, and the transverse inclined bar is inclined arranged on the cross section of the line. As that transverse incline bar vertically supports the cross beam, the vertical deflection of the cross beam unde the action of dead load and live load is greatly reduced, and the height of the cross beam of the ultra-wide truss-wide bridge deck system is effectively reduced, thereby realizing the effect of saving material and reducing self-weight.