Abstract: In order to study characteristics of discharge channels of air plasma induced by high-energy pulsed CO₂ laser, a charging and discharging experimental setup of high voltage capacitor was established, in which the pulsed laser beam was focused by a parabolic reflector to trigger the plasma channel in the adjustable gap between a disk-like electrode and a needle-like electrode. Based on the measurements of electric parameters and emission spectra, the characteristics on start-up, impedance and plasma density of the discharge channel were analyzed. It is found that the start-up time become much shorter benefited from the high pulsed-energy and coaxial structure of laser beam and discharge direction, for a plasma channel with length of 50mm, the start-up time of the discharge was only about 2μs; the discharge channel has rather low impedance of 1Ω~2Ω, and this impedance has a decreasing tendency with the increasing of discharge voltage, which has no significant correlation with the length of plasma channel; the electron density after the laser-induced breakdown and before the electric discharge is on the level of 10¹⁹ cm^-3 calculated from the Stark broadening of the emission lines, though the emission become much stronger after the startup of electric discharge, the plasma density keeps decreasing. These results will be helpful for the application of laser-induced plasma channel.