Fast Linear Transformer Driver(FLTD) is an economic and effective technical routine for constructing high-current high-voltage pulsed power drivers, but its circuit topologies, multi “bricks” in series and parallel, put forward strict technical requirements on gas spark switches. Aimed at the problem of pre-fire, which seriously restricts the reliability and stability of FLTD facilities, researches of this paper are carried out on the focus of pre-fire in FLTD gas spark switches. Three-electrode field distortion gas switch and multi-stage multi-channel gas switch are employed, and the influence of discharge current and switch parameters on pre-fire characteristics is studied at ±100 kV. The results show that the self-breakdown voltage of both switches fits well with Weibull distribution. Increasing the switch pressure and shortening the gap length can help decrease switch trigger delay, but directly increase pre-fire probability. Under 29 kA current amplitude and 75% working ratio, the discharge dispersivity of the three-electrode field distortion gas switch is about 4%, while the dispersivity of the discharge of the six-stage multi-channel gas switch is more than 15%. Both types of switches have obvious early discharge phenomena. The uneven distribution of potential of each gap in six-stage switch is thought to be responsible for the increase of pre-fire rate. By resistors parallel-connected with each gap to mandatorily realize voltage sharing, the pre-fire rates of the three-electrode field distortion and the six-stage gas switch decrease to 2% and 5%.