The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method for controlling a terminal in a base station of a mobile communication system, according to an embodiment of the present application, comprises the steps of: selecting at least one candidate terminal for offloading; obtaining information on a neighbor cell of at least one of the candidate terminals; obtaining throughput improvement information according to offloading on the basis of information on the candidate terminal and load information of the neighbor cell of the candidate terminal; obtaining information on a target cell corresponding to the candidate terminal on the basis of the throughput improvement information; selecting a target terminal to be offloaded from the candidate terminals on the basis of the throughput improvement information corresponding to the target cell; and transmitting, to the target terminal, a message instructing offloading to the target cell corresponding to the target terminal.