We fabricated the 1-inch diode type flat lamp using CNTs, which were grown directly on soda-lime glass substrate at 600 ∼ 650 $^{circ}C$ by thermal chemical vapor deposition(CVD) of acetylene gas. Turn- on field was about 2.8 V/${mu}{ extrm}{m}$. We observed that uniform and high brightness had been obtained. The brightness of CNT flat lamp was measured up to about 14 kcd/$m^2$ at 2000V in spacing of 500 ${mu}{ extrm}{m}$. The results showed that the CNTs were very good emission source and suitable for application in the lamp.