Abstract: In order to optimize the structure of multi-gap gas switch used in fast linear transformer driver(FLTD) module, the electric field distribution of gas switches with different structured electrodes before and after trigger were simulated. The effect of pressure balance measures on the electric field distribution of the gaps in the gas switch before trigger was studied by applying the new circuit model of the gas switch. Moreover, the relationship between the stray capacitances of the middle electrodes and the electric field distribution in the gas switch after trigger was studied. The results show that the ring electrode of circular section is conducive to the formation of a stable multi-channel discharge, and it can reduce the switch inductance and jitter; the DC voltage characteristics of the switch can be effectively improved by using the resistor of the same resistance in parallel between the gaps. At the trigger moment, the voltage distribution of each gap is mainly related to the trigger voltage rise time, the resistance and stray capacitance, and the shorter the trigger voltage rise time is, the more obvious the effect of the stray capacitance on the gap voltage distribution is.