The utility model provides a center island atress type cavity is prefabricated cavity component of assembled for superstructure, prefabricated cavity component includes that reinforced concrete cross rib roof beam, reinforced concrete indulge girt strip and filling member, prefabricated cavity component has two reinforced concrete at least and indulges girt strip and a plurality of reinforced concrete cross rib roof beams, every two reinforcing bars about being provided with in the reinforced concrete cross rib roof beam, every be provided with steel flat rack in the vertical girt strip of reinforced concrete, steel flat rack with carry out fixed connection through support fixing device between the reinforcing bar, have at least one to reserve not deposit concrete of angle in the girt strip of prefabricated cavity component, filling member sets up in moving about freely and quickly the space between the vertical girt strip of criss -cross reinforced concrete cross rib roof beam and reinforced concrete. The utility model discloses advantage that can the industrialization of make full use of mill, construction, environmental protection, matter weight, cost, the work efficiency scheduling problem that current system exists can be solved to the prefabricated cavity component of this assembled, carry out transformation and upgrading, update to current assembled cavity superstructure structure system, have fine economic nature and suitability.