The present disclosure is a research which has been conducted with the support of the “Cross-Departmental Giga KOREA Project” of the government (the Ministry of Science and ICT) in 2017 (No. GK17N0100, Development for mmWave-based 5G mobile communication system). The present disclosure relates to a communication technique for convergence of a 5G communication system for supporting a higher data transmission rate beyond a 4G system with an IoT technology, and a system therefor. The present disclosure may be applied to an intelligent service (for example, smart home, smart building, smart city, smart car or connected car, health care, digital education, retail business, security and safety-related service, etc.) on the basis of a 5G communication technology and IoT-related technology. The present disclosure provides a system and a control method therefor, which can prevent, when a dual connectivity scheme is used, delay and data loss due to an operation of releasing and adding a secondary node cell or a process of resetting a user plane and updating a security key and a procedure of forwarding data between user planes through a common anchored user plane and changing (updating) a path between the user plane and a core.