A method for allocating a central processing unit resource to a virtual machine, including determining, according to a change in the number of virtual machines in an advanced resource pool, the number of allocated physical cores in the advanced resource pool; and adjusting, according to the number of the allocated physical cores in the advanced resource pool, the number of allocated physical cores in a default resource pool, where the advanced resource pool and the default resource pool are resource pools that are obtained by dividing physical cores of a central processing unit according to service levels of the resource pools.