Embodiments of the present invention disclose a method and an apparatus for allocating a memory space with a write-combine attribute, including: determining, when resources of devices are scanned, a type and a size of a resource required by each device; determining, after the scanning of the resources of the devices is completed, a total size of write-combine memory spaces required by all first devices; then determining a starting address used to allocate a write-combine memory space to the first devices; and allocating one memory space jointly to all the first devices and allocating, from the one memory space, a sub-memory space to each first device. According to the embodiments of the present invention, a memory space with a write-combine attribute can be allocated to devices in a more reliable manner and by using a relatively simple allocation method.