A server device and a method of sharing a basic input/output system (BIOS) include a plurality of mainboards, a circuit board, and a memory unit, and a switching unit disposed on the circuit board. A single memory unit stores a plurality of BIOS entity program segments respectively corresponding to a mainboard model, and transmits the BIOS entity program segments corresponding to the model of the mainboard for receiving the BIOS to the mainboard through the switching unit, so that the mainboards of various models may share the BIOS.