In order to investigate high-power TEA CO2 laser, a high-power rotating spark switch is chose as a device of power switch. Therefore a pulsed exciting power supply is developed including a high voltage resonant charging circuit, a high anti-jamming switching trigger, a rotating spark switch and a draw-out L-C reverse circuit. The measurement and the research are conducted in the high-power TEA CO2 laser. The experimental results demonstrate that this pulsed exciting power supply developed by our lab can totally satisfy the special requirement of the high-power TEA CO2 laser. The repetition rate can adjust arbitrarily at the range of 100~400 Hertz, the output working voltage is up to 40kV~50kV, the average power of power supply is larger than 220kW and the peak power of this device is as high as 1000MW.