The invention relates to the field of high-voltage equipment, in particular to a prefabricated ceiling and a secondary device prefabricating bin using the same. The prefabricated ceiling comprises a frame and door plates assembled on the frame, the frame comprises cross bars and vertical bars, the cross bars or the vertical bars are wiring bars, the inner sides of the wiring bars are provided with wiring grooves, the inner side walls of the wiring grooves are provided with through wire outlets, the door plates are hinged to the frame, and door lock mechanisms are arranged between the frame and the door plates. During use, the prefabricated ceiling can be assembled at the top of the secondary device prefabricating bin by fixing the frame only. Furthermore, by the aid of the prefabricated structure, the prefabricated ceiling can be intensively manufactured in physical factories and better quality can be guaranteed. Above all, the prefabricated ceiling solves the problems that existing ceilings of the secondary device prefabricating bin are low in manufacturing efficiency and quality is not easy to guarantee.