A method for recovering a basic input/output system (BIOS) image file of a computer system is provided. The method includes steps of: controlling a switch unit of the computer system to switch from a first state to a second state when the BIOS image file is to be updated; reading a current BIOS image file so as to store the same as a backup; controlling the switch unit to switch back to the first state; determining whether a command is received within a first predetermined time period when the BIOS image file is successfully updated to a new version of the BIOS image file; and when negative, controlling the switch unit to switch to the second state and writing the backup of the current version of the BIOS image file.