Abstract: To study the process of micro-gap gas discharge under different pressures,the experiment of the micro-discharge for the gaps ranging from 1 μm to 100 μm under 1-100 kPa is presented,and the results are discussed. With the decrease of the gaps,the deviation between the breakdown curves and the traditional Paschen curve increases when the electrode distance is less than 100 μm and the pd value is less than about 80 Pa·cm,and the same pd value corresponds to multiple breakdown voltages. The breakdown field strength of each electrode spacing under different pressures is analyzed,and it is found that the breakdown field strength is close to 108 V/m when the electrode spacing is below 5 μm. At this time,the electrode breakdown is dominated by field emission. The ratio of the effective secondary coefficient of field emission to Townsend secondary emission coefficient is estimated under different gas pressures. Different breakdown mechanisms in the range of different electrode distances are founded,and the ion-enhanced field effect has been found to play an important role in field emission in several microns of electrode gaps.