Performance of a high repetition-rate long-pulse UV-preionized TE CO2 laser with an active volume of 1.17 L utilizing pulser/sustainer discharge technique is investigated in detail. The laser operates with a high repetition-rate of 100 Hz and output laser pulse full width at half maximum (FWHM) of 23.0 μs. The voltage/current waveforms under stable glow discharge and arc discharge are given respectively. The laser output pulse energy varies from about 0.40 J to 4.0 J as the charging voltage on the sustainer circuits rises from 12 kV to 30 kV. Under the same sustainer charging voltage, the laser output power increases linearly with the pulse repetition rate. With sustainer charging voltage of 22 kV and repetition rate of 100 Hz, the laser output power only decreases from the highest 257 W at the beginning to 247 W at the end of 10-min continuous operation. All the experimental data show that, compared with the conventional TE CO2 laser with low inductance quick discharge, it generates a long laser pulse profile containing greatly suppressed initial gain-switch spike, tolerates arcing discharge in repetition rate operation, and decreases more slowly under high repetition-rate long-time operation.