The present disclosure relates to a communication system and technique that may be applied to intelligent services based on a 5G communication technology and an IoT-related technology. The present disclosure provides a method for data transmission of a terminal in a wireless communication system that includes inputting a packet data convergence protocol packet data unit (PDCP PDU) output from a PDCP entity to a first radio link control (RLC) entity and a second RLC entity. The method also includes inputting a first radio link control packet data unit (RLC PDU) output from the first RLC entity and a second RLC PDU output from the second RLC entity to a medium access control (MAC) entity and transmitting a medium access control packet data unit (MAC PDU) output from the MAC entity through a first physical layer (PHY) entity and a second physical layer entity.