The present disclosure relates to a communication technique that fuses IoT technology with a 5G communication system to support a higher data transfer rate than a 4G communication system, and a system therefor. The present disclosure may be applied to intelligent services (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, health care, digital education, retailing, security and safety related services, etc.) on the basis of 5G communication technology and IoT related technology. The present disclosure relates to a 5G or pre-5G communication system for supporting a higher data transmission rate than a 4G communication system such as LTE. An embodiment of the present invention relates to a method and a structure for processing data for packet duplication. According to the embodiment of the present invention, disclosed are a radio bearer setup method, a packet duplication operation, and a buffer status reporting method, which are for use in performing packet duplication.