Embodiments of the present invention provide a startup method and apparatus, and a computer system, which relate to the computer field and are used to reduce a probability of a system startup failure caused by occurrence of a bad block in Nand-Flash. The method includes: when a CPU fails to start a system, receiving, by a startup apparatus, a backup area selection instruction, where the backup area selection instruction is used to instruct the startup apparatus to read a boot loader from a backup area of Nand-Flash; receiving a program read instruction sent by the CPU, where the program read instruction includes a primary area address of the boot loader in the Nand-Flash; acquiring a backup address of the boot loader in the Nand-Flash from a correspondence between primary and backup addresses according to the primary area address; reading the boot loader from the backup address in the Nand-Flash; and sending the boot loader to the CPU, so that the CPU starts the system according to the boot loader.