The present invention provides a user equipment registration method, a radio network controller, and a user equipment, where the user equipment registration method includes: receiving, by an RNC, an initial direct transfer message sent by a UE that supports a MOCN, where the initial direct transfer message carries a PLMN ID selected by the UE; sending a redirection request to a core network of one of operators that form the MOCN, and receiving a PLMN ID delivered to the UE by the core network that is of the operator and accepts the foregoing redirection request; and sending a downlink direct transfer message to the UE, where the downlink direct transfer message carries the PLMN ID delivered to the UE by the core network that is of the operator and that accepts the foregoing redirection request, and the PLMN ID delivered to the UE by the foregoing core network that is of the operator and accepts the redirection request is the PLMN ID selected by the UE. Therefore, consistency can be ensured between the PLMN ID delivered by the core network of the operator and the PLMN ID requested by the UE. In this way, the UE can register successfully, disconnection of the UE from a network is avoided, and user experience is improved.