A multicast/unicast admission control method, a multicast/unicast admission control device, and a multicast/unicast admission control system are provided. In the method, through centralized resource control of a resource and admission control subsystem (RACS), sharing of multicast/unicast resources is realized. The RACS allocates and authorizes resources to an access node (AN), the AN manages the obtained multicast resources under the authorization, and the resource allocation is adjusted through interaction when the multicast resources of the AN or the resources of the RACS are not sufficient.