A system and a method for managing an expansion read-only memory (ROM), and a management host thereof are provided. The management host is connected with a computer host through a bridge. The management host establishes an address lookup table to assign a virtual function and an expansion ROM corresponding to the virtual function. When a request is issued by the computer host to obtain a size of the expansion ROM, the management host provides data in a shadow register block corresponding to the expansion ROM to the computer host according to the address lookup table. The computer host assigns a memory block in the computer host to the expansion ROM according to the data in the shadow register block. When a request is issued by the computer host to obtain data of the expansion ROM through the bridge, the management host provides the data of the expansion ROM to the computer host according to the memory block.