The present invention discloses a method for assigning the carrier frequency in a trunking system, which includes: after the base station subsystem receiving a group call request, it assigns a carrier frequency reference for this group call, by which to establish the forward channels of the group users managed by the base station subsystem. With the method offered by the present invention, all the group members under a base station subsystem could be established on the same carrier frequency reference as far as possible, thereby sharing of the wireless channels.