Abstract: Effect of gas flow velocity on repetitive operation performance was experimentally investigated for a spark gap switch with a compact gas blowing system, based on a compact repetitive Tesla transformer. The experimental results were presented and analyzed. The conclusions are shown as follows: (1) for a repetition rate lower than 50 Hz, the pulse-to-pulse instability (RMS) of the breakdown voltage of the spark gap switch is smaller than 5% and it is possible to spare a gas blowing system; (2) given a gas flow velocity, there exists a critical repetition rate for the stable operation of the spark gap switch; (3) for the repetitive operation of the switch in a given repetition rate, there exists an optimal fan frequency, which is linear with the repetition rate and can be determined by expe