Abstract: The present invention provides a flat fluorescent lamp (FFL), including a first substrate, a second substrate, a discharging gas, an electrode set, a dielectric layer and a fluorescent material. The first substrate has at least a first cavity and the second substrate has at least a second cavity. The first substrate and the second substrate are oppositely connected to each other, thus allowing the first cavity together with the second cavity define a discharging space thereby. The discharging gas, the fluorescent material and the electrode set are all disposed in the discharging space. The electrode set is interposed between the first cavity and the second cavity and is adapted for providing a discharging electric field mostly distributed in the discharging space defined therein. In addition, a liquid crystal display (LCD) device using such an FFL is also proposed.