The invention claims a multicast or unicast admission control method system and device. The multicast admission control method includes the network equipment receives multicast request and performs admission control operation for multicast resource according to the multicast request; when the multicast resource is deficient sending external resource request to the resource admission control equipment and performs multicast operation according to the result of admission control operation corresponding to external resource request returned by the resource admission control equipment. The unicast admission control method includes the resource admission control equipment receives unicast resource request and performs unicast resource admission control operation according to unicast resource request; when the unicast resource is deficient sending external resource request to the network equipment; the resource admission control equipment performs unicast operation according to result of admission control operation responding to external resource request returned by the network equipment. The invention ensures fast switch for multicast service channel in the condition of sharing resource of multicast service and unicast service and the realization manner is simple.