A DC discharge method is introduced to improve the production of F atom for all gas-phase iodine laser(AGIL). Characteristics of the DC discharge are studied for the usage of cylinder electrode. About 3 kW input power is obtained when dissociating the mixture of NF3 in He by different balance resistance. Production of F atom is measured with spectrometer(CCD) and the production of F atom is about 1.3~1.5 with one NF3 molecule.