Abstract: Embodiments of the present invention provide an SLA-based resource allocation method and an NFVO. The method includes: receiving, by an NFVO, a network service instantiation request, where the network service instantiation request includes an identifier of an SLA of a network service; determining, by the NFVO based on the identifier of the SLA of the network service, an NFVI SLA parameter required for instantiating the network service; further obtaining, from a VIM based on the NFVI SLA parameter, a virtual resource meeting a requirement of the NFVI SLA parameter; and instantiating the network service based on the obtained virtual resource. In the method, the NFVO considers the NFVI SLA parameter when applying for the virtual resource, so that the obtained virtual resource meets a user requirement and a qualification hit rate of resource application is improved.