Disclosed is a method for setting a common channel for a packet data service by an SRNC through a UE and a DRNC when the UE is handed over from a first Node B to a second Node B as the UE moves to the second Node B, in a mobile communication system. The SRNC transmits service parameters including bit rate information for the packet data service to the DRNC, and receives information on a common channel determined based on the service parameters from the DRNC. The SRNC transmits information on the determined common channel to the UE through the DRNC and the second Node B, to allocate the determined common channel to the UE.