The present invention relates to a method and apparatus for transmitting data in a wireless communication network. A base station having information of idle mode user equipment transmits a connecting operation mode to user equipment when the idle mode user equipment is connected to the base station. The user equipment transmits small-sized data together with a connection request completion message to the base station. The base station transmits, over a network, the data received from the user equipment, without being interlinked with a mobility management entity, and the user equipment returns back to an idle operation mode after data transmission. Thus, signaling the base station for acquiring context information of the user equipment can be reduced in order to provide the user equipment with an efficient data transmission environment.