To meet the requirements of a pulse power device with MA-level microsecond discharge current

a four-electrode UV pre-ionization gas switch was designed and its structure was optimized

and the relative research was carried out. The experiments show that UV pre-ionization and high-amplitude trigger voltage are important factors to realize short delay and low jitter under the wide operating coefficient of the switch. With a trigger voltage of 140 kV

rise time less than 30 ns（the 10%～90% peak voltage time）

the synchronous conduction of two pre-ionization gas switches is realized under the condition of 40%～70% operating coefficient（percentage of the switch operating voltage divided by self-breakdown voltage）. Between different operating coefficients

the dispersion（extreme difference） of the delay time is less than 20 ns. The switch has a current flow capacity of no less than 230 k A and 18 C/shot

after 150 times of large-current experiments

the switch self-breakdown voltage changes less than 2%

and the triggering characteristics are not significantly deteriorated. The switch designed in this paper solves the problem of short-time delay and low jitter under the condition of large capacity and a wide operating coefficient

and meets the needs of engineering applications. It is of great significance to further realize the synchronous conduction of parallel operating large-capacity gas switches.