Provided are an apparatus and a method for manufacturing a flat fluorescent lamp. The fluorescent lamp includes a plurality of discharge channels, a gas inlet connecting to the discharge channels, and an exhaust pipe connecting to the gas inlet. The process for manufacturing the fluorescent lamp includes exhausting air from the discharge channels through the exhaust pipe, diffusing a mercury vapor within the discharge channels, blocking a passage between the gas inlet and the most outer channel, and removing the gas inlet and the exhaust pipe.