We emphatically investigated the discharge characteristics driven by direct-current（DC） voltage in micro-channel which consists of plate-to-plate electrodes separated by two parallel dielectric layers with micro-spacing. The breakdown voltages and current-voltage curves of the micro-channel structure in atmospheric air and nitrogen were measured by experiments

respectively. The experimental results show that

in both air and N2

the breakdown voltage increases as the channel height（or the spacing between the two dielectric layers） changes from 90 to 20 μm. Moreover

we investigated the breakdown characteristics of micro-channel structure in nitrogen by PIC/MCC simulation. The results show that the accumulation of electrons on the dielectric layers plays the key role in the breakdown in micro-channels which makes the great reduction of electron density in the micro-channel. The smaller the channel height is

the much more the electrons lose on the dielectric surface when moving toward the anode

resulting in a higher breakdown voltage.