1. A method for implementing memory migration on a computer, comprising: migrating, by a basic input-output system (BIOS) of the computer, data in a memory to be migrated to a first unusable memory of an operating system of the computer; wherein the first unusable memory is converted in advance of implementing the memory migration from an original usable memory of the operating system, and wherein the first unusable memory is reserved for the operating system, and the first unusable memory is unmodifiable by and inaccessible to the operating system, but is operable by the BIOS; storing, by the BIOS, a mapping relation between a physical address of the memory to be migrated and a physical address of the first unusable memory; determining, when the operating system accesses a target physical address, whether a mapping relation corresponds to the target physical address stored by the BIOS; and accessing, when the mapping relation corresponds to the target physical address that is stored, data in the first unusable memory according to the mapping relation corresponding to the target physical address.