A method and apparatus for transmitting data in a wireless communication system is provided. A user equipment (UE) establishes dual connectivity with at least one first cell and at least one second cell, receives an indication which indicates that a data transmission path of a radio bearer is to be configured for the at least one first cell, configures the data transmission path of the radio bearer for the at least one first cell, and transmits data via the data transmission path on the at least one first cell.