In order to study the micro-characteristics of the micro-gap discharge in an explosive environment

taking the international standard IEC spark test device as the research object

we established a simulation model of two-dimensional parallel plate discharge in a gas and air mixed gas environment with a tungsten wire as the anode and a cadmium disc as the cathode. The particle method（PIC-MCC） was used for simulation to study the dynamic process of micro-gap discharge with a voltage between parallel plates of 295 V and a pole pitch of 5 μm. The micro-scale discharge mechanism in an explosive gas environment was analyzed at the micro level

and the electrode was discussed. The influence of factors such as distance and gas concentration on microscopic particles during the discharge process reveals the influence of these factors on the discharge voltage and current characteristics. The final simulation results show that the main mechanism of micro-gap discharge when the pole distance is 5 μm is field emission

rather than gas discharge characterized by impact ionization and electron avalanche. The number of CH ion particles during the discharge process negligibly changes. When the pole distance is 15 μm

the main mechanism of micro-gap discharge is gas avalanche ionization. The methane concentration in the mixed gas will affect the discharge result as follows: when the methane concentration is in the range of 3.5%～13.5%

the anode absorption current during discharge will increase by 10 mA with every 5% increment in the concentration. At the microscopic level

as the methane concentration in the mixed gas continues to increase

the rate of CH ion generation will also increase

and the methane gas will increase. The contribution of the discharge process is also increasing.Moreover

a micro-gap discharge test platform in an explosive environment is built to further verify the macroscopic characteristics of the change of the microscopic particles when the distance between the electrodes is changed.