In this report, experimental results on glow discharge in low pressure air are presented. Some basic properties are obtained at first, the relation between discharge starting voltage and gas pressure, the relation between sustaining voltage and discharge current, and optical radiation and discharge mode. Experiments are carried out with a miniature hollow cathode of 1.85mm and 0.8mm in diameter at the center of brass plate. Products of gas pressure and discharge path length having lowest starting voltage for these cathodes in air are 0.407cmTorr at 505V and 0.400cmTorr at 600V respectively. When strong optical emission is radiated from a hollow cathode, discharge current increase noticeably with small change in sustaining voltage, and cathode fall region is confined in a miniature hollow cathode. Then measured electron temperature of hollow cathode discharge is about 1eV, which decreases with increase of discharge current or that of gas pressure.