Disclosed herein is a 10-gigabit Ethernet line interface apparatus and method of controlling the same. The apparatus has N network processors, a frame multiplexing and demultiplexing block, a 10-gigabit extender sublayer processing block, a 10-gigabit Ethernet physical layer processing block, a 10-gigabit physical layer control logic, a line interface control logic, and a line processor. The N network processors are connected to the switch fabric unit. The frame multiplexing and demultiplexing block provides GMII and XGMII between the N network processors and a 10-gigabit extender sublayer processing block. The present invention can improve transmission speed and packet processing performance of a physical layer to a 10 Gbps level while maintaining basic frame standards of a 1-gigabit Ethernet switch apparatus.