Abstract: A computer system, using a power button to switch from one BIOS to another, includes a power button, a detection device and a switch circuit. The power button is electrically coupled to the computer system. The detection device is electrically coupled to the power button, and outputs a switch signal and a boot signal when the power button is continuously pushed for a switch time value, in which the boot signal is used to execute a boot procedure in the computer system. The switch circuit is electrically coupled to the detection device, and switches from a first BIOS to a second BIOS used for the boot procedure, in accordance with the switch signal. A method of using a power button to switch from one BIOS to another is also disclosed.