Abstract: The gas switch in the linear transformer driver (LTD) module can form a discharge loop with the storage capacitor of the remaining bricks via isolation resistors after pre-fire during the charging phase. In this case, the switch cannot turn off immediately, threatening the charging reliability and consistency of the entire LTD module. This paper first analyzes the current characteristics of the pre-fired switch based on a single-stage LTD circuit simulation model. After the pre-fired brick is discharged, there are still several amperes of leakage current in the switch. An equivalent experimental platform was established to investigate the insulation recovery characteristics of the pre-fired switch with a RC holding current. Moreover, the effects of the storage capacitor charging voltage, switch operating pressure, and switch gap number on the duration and the cutoff value of the holding current were explored, respectively. The experimental results indicate that a holding current maintaining tens of milliseconds is formed after the switch breakdown, which extends the time required for the insulation recovery of the gas switch. Raising the switch operating pressure slightly increases the duration and decreases the cutoff threshold of the holding current. The other two factors do not affect the holding current characteristics. In most cases, the cutoff threshold is 0.4~0.6 A. There is a maximum value for the duration of the leakage current in the pre-fired switch when the isolation resistance changes. Considering the isolation ability and impact on charging consistency of the isolation resistor, it is recommended that the isolation resistance could be set to 50~100 kΩ.