Abstract: High speed ejected plasma, generated by the discharge in an actuator, can be applied as a trigger to gas gap switch which is working at low coefficient or with wide gap. This paper studies the influence of working conditions of gas switch on the discharge characteristics of ejected plasma triggered gas switch .The effects of gap distance, gas type, gas pressure, switching coefficient and cooperation mode of trigger pulse polarity and main voltage polarity on the discharge characteristics of ejected plasma triggered gas switch were studied by experiments. The results indicate that the ejected plasma triggered gas switch can be reliably and rapidly triggered with switching coefficient of about 10% . When the gas pressure of N₂ in the switch is 0.5 MPa and the gap distance is 5 mm, the delay time and jitter are 11.7 μs and 1.42 μs, respectively. When the distance increases to 18 mm, the probability is reduced, the delay time increases to 19.7 μs. When the switching coefficient increases from 10% to 60%, the delay time decreases from 11.7 μs to 1.1 μs. With the same self-breakdown voltage, high pressure, short gap distance, negative trigger pulse and positive main voltage are better best choices to reduce the delay time.