Method for automatically restoring basic input and output system image files and computer system

A method for automatically restoring basic input and output system image files is executed by a computer system, which comprises a flash memory storing an image file, a processor and a switch unit performing switching between a first state and a second state. In the first state, the flash memory is electrically connected with a control chip group and in the second state, the flash memory is electrically connected with a controller. The method comprises the following steps: when an update instruction is received, the processor outputs a notification instruction; The controller switches the switching unit to the second state; The controller backs up the image file. When the backup is completed, the switching unit switches back to the first state; The controller judges whether an update successful instruction is received or not. When it is judged to be no, the switching unit switches to the second state; The controller overwrites the image file it backed up to the flash memory. 种自动回复BIOS映像档的方法，由计算机系统执行，其包括存有映像档的