Provided are a communication method and system enabling convergence of 5G communication and IoT technology to achieve higher data rates for beyond 4G communication systems.In addition, provided is a method for transmitting a power headroom report (PHR) by a user equipment (UE) in a mobile communication system. The method includes: receiving a first PHR configuration information for a first base station (first ENB); receiving a second PHR configuration information for a second ENB; generating, when the UE has dual connectivity to the first ENB and the second ENB, a dual connectivity PHR containing PHR information for the first ENB and second ENB based on a dual connectivity PHR format; and sending the dual connectivity PHR. There is also provided a user equipment supporting the above method. There is further provided a base station and operation method therefor that enable the user equipment to have dual connectivity.