A method of booting a computer is provided. The computer includes a processing unit, and a baseboard controlling unit storing a prioritized option of boot device and a prioritized type of boot hard disk. The method includes steps of: the processing unit sending a first query about the prioritized option of boot device to the baseboard controlling unit; in response to receiving the prioritized option of boot device from the baseboard controlling unit, when the processing unit determines that the prioritized option of boot device is hard disk, the processing unit sending a second query about the prioritized type of boot hard disk to the baseboard controlling unit; and in response to receiving the prioritized type of boot hard disk from the baseboard controlling unit, the processing unit booting the computer from a hard disk that corresponds to the prioritized type of boot hard disk.