The stimuli circuit of the XeCl excimer laser has a great effect on the output characters of the laser. In order to improve the output character of the laser,the Spark Gap Switch（SGS） was originally and satisfactorily used to control the instant high current trigger signal of the XeCl excimer laser which was made by ourselves.To begin with, the design of the structure of the XeCl excimer laser was discussed, and then the circuit parameter of the laser was determined. Secondly,to deal with the problems in the experiments,the current foldback, optical coupler insulation and electromagnetic shielding were used to optimize the circuit performance of laser. Finally, the measured data shows that the laser worked stably and the output characters reached the design values by the improved methods.Thus it would offer the reference of. the improvement of the laser＇s output characters.