Abstract: The primary objective of this article is to research the effect of pulsed discharge spark resistance on output pulse front edge of gas spark switch. The analysis on characteristics of spark discharge resistance is an important foundation to study switching energy loss, arc thermal plasma physical state, and repetitive switch insulation recovery characteristics, etc. Combined with the gas spark switch circuit model established, switch inductance and resistance have been taken into account to analyze the impact on the pulse front edge. For the high voltage gas switch with large gap, spark resistance is the dominating factor affecting the front edge of output pulse.