The invention relates to a large-headroom flanged storable-function steel-framed centrally braced system and belongs to the field of structural engineering. All components of the system herein are processed in a factory; connecting and mounting are performed completely through high-strength bolts; therefore, the high requirement on the component processing precision and quality is easy to meet, and quick assembly is easy to implement. A diagonally braced system herein is prefabricated anti-buckling Y-shaped bracing, energy-dissipating elements are arranged in the positions where diagonal braces are provided; therefore, the stability of the diagonally braced system and overall lateral load resistance of structure are improved. A door opening can be set in the position where the bracing is provided, so that the design form is more flexible, and different structural forms can be satisfied. An upper flange connection plate is of inner cover plate form; when the inner cover plate deforms, the inner cover plate may gain tight contact with an inverted-L-shaped web shear plate, the inverted-L-shaped web shear plate helps control buckling deformation of the upper flange cover plate, and therefore, buckling resistance is achieved.