Abstract: Time-resolved photos of the discharge of TEA(transversely excited atmospheric pressure) CO2 laser taken by ICCD camera were analyzed. Quantitative data on the spatial distribution and the temporal development of the discharge were given. Second glow originated from the selfsustained discharge was found in the case of usual capacitor discharge circuit (long pulse discharge circuit). The light emission of the preionization with a short pulse discharge circuit using a magnetic compress switch formed later, but the interval between preionization and main discharge was shorter. For both long pulse discharge circuit and short pulse discharge circuit, the formation of cathode sheath occurred in the late stage of discharge. Short pulse discharge circuit has advantages to obtain shorter pulse dur