The construction of a low impedance and high intensity flash x-ray (FX) generator for biomedical radiography is described. This generator consisted of the following components: a high voltage power supply, a low impedance transmission line with a high voltage coaxial condenser (120kV-0.15μF), a compressed-gas (SF6) gap switch with a small-sized trigger device operated by light through a fiber, a trigger delay device, a vacuum pump system, and two evacuated FX tubes, each of a different type, with eight coaxial cables. The FX generator may be used for condenser charging voltage of 50 to 120kV. The electric pulse width of the FX output varied according to the beam quality, anode-cathode (A-C) space, and others, and ranged from 0.1 to 0.4μs. The original FX intensity from the source was determined by the condenser charging voltage and A-C space, and the maximum intensities of the Type A and B tubes were about 100 and 200mR at lm/pulse, respectively. The FX quality was determined by the average voltage of FX tubes, the efficiency of electron beam conversion into FX due to the configuration between the anode and cathode electrodes, and the insertion of metal filters. The effective focal spot varied due primarily to the configuration of electrodes and the insertion of filters. Various clear FX images achieved with a digital radiography system were obtained by controlling the FX intensity, the quality, and the size of the effective focal spot.