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. The present disclosure provides a method and a device of power control for a Uu uplink transmission and a V2X transmission. Specifically, the present disclosure provides a method for determining the transmission power based on the circumstance of synchronous/asynchronous carriers, a minimum time delay of preparing the transmission power of the V2X and Uu uplink transmission, and an actual time delay of V2X from a resource reselection to a transmission. By this method, the transmission efficiency of the V2X and the Uu uplink transmission can be ensured.