Abstract: A three-electrode field-distortion gas spark switch used for linear transformer drivers is developed. The switch is insulated with SF6. The size and inductance of the switch is small, and the inductance is experimentally estimated at about 67 nH. When the switch operates at 80 kV charge voltage and 70% working ratio, the delay and jitter are 40.0 ns and 2.8 ns respectively. The influences of the electrode material on the self-breakdown and trigger characteristics are experimentally studied. The results indicate that the switch of CuW electrode has a smaller deviation of self-breakdown voltage, smaller delay and jitter, lower prefire probability and less electrode erosion than that of copper electrode. Compared with copper material, CuW material may be more suitable for three-electrode field-distortion gas switch.