The present invention relates to a method of relocating a serving radio network controller (RNC) in a radio telecommunication system for switching a first RNC which is assigning radio and network resources to a user equipment (UE) to a second RNC replacing the first RNC for assigning radio and network resources to the UE continuously. The radio telecommunication system also comprises a core network which comprises a plurality of serving GPRS support node (SGSN). The first RNC is coupled to a first SGSN of the plurality of SGSNs. The second RNC is coupled to a second SGSN of the plurality of SGSNs. The method of the invention mainly performs the routing path switch between the SGSN and the RNC in the SGSN level, and is used in two modes: intra-SGSN mode and inter-SGSN mode.