Embodiments of this application describe a computer boot method, a controller, a storage medium, and a system, to improve a boot security level of a computer, and avoid a security risk caused by using a tampered boot program file. In a method, a controller is separately connected to a computer hardware system and a BIOS file storage apparatus. The controller obtains a first boot program file in the BIOS file storage apparatus when the controller is powered on and run. The controller establishes a connection between the BIOS file storage apparatus and the computer hardware system when the first boot program file is successfully checked, so that when the connection between the BIOS file storage apparatus and the computer hardware system is successfully established, the computer hardware system completes power-on and running by using the first boot program file.