The present invention discloses a method, system, and device for admission control and pertains to the communications field. The method includes: admitting a subscriber for watching a multicast video only if each multicast bandwidth management device has sufficient remaining bandwidth after receiving a multicast video request from the subscriber; refusing the subscriber for watching the multicast video if any multicast bandwidth management device has insufficient bandwidth and fails to borrow bandwidth from a unicast bandwidth management device; and after receiving a unicast video request from the subscriber, admitting the subscriber for watching a unicast video only if remaining unicast bandwidth corresponding to a multicast bandwidth management device in each level is sufficient, or else, refusing the subscriber for watching the unicast video. Through bandwidth negotiation between the unicast bandwidth management device and each multicast bandwidth management device, admission control is implemented.