A resource and admission control method and a resource and admission control sub-system are provided in the present invention. The method is: the subscription information during the subscription process between a user and a network attachment sub-system including: an adaptive Quality of Service (QoS) parameter of a media type or a service, the adaptive QoS parameter representing the maximum value for the resource and admission control sub-system regulating the resource occupancy of the media type or the service; during the process of the resource and admission control, when the current resource cannot satisfy the service resource request initiated by the user, the resource and admission control sub-system judges whether to regulate the resource occupancy of the media type or the service to satisfy the resource request according to the adaptive QoS parameters of the various different media types or services included in the user session; in the case of the judging result being ‘yes’, the resource and admission control sub-system reduces the resource occupancy of the media type or the service with the adaptive QoS parameter from low to high according to the priority of the media type or the service and accepts the resource request, otherwise rejects the resource request.