Abstract: Non-equilibrium plasma can assist lean methane-air combustion, but the numerical simulation of this process is not yet in-depth. This paper establishes a simplified plasma-assisted methane combustion mechanism, and a one-dimensional fluid model is used to simulate the micro-scale DBD non-equilibrium plasma-assisted lean methane-air combustion process. The simulation results show that plasma discharge can effectively promote the combustion reaction at a lower initial temperature. With the increase of discharge voltage, the number density of electrons in the discharge space increases significantly, and the combustion temperature is effectively increased. The numerical simulation results can reflect the changing trend of the primary active particles. In this stage, the increase of Ar content or the molar ratio of CH₄ to O₂ will slightly increase the combustion temperature, but the impact is negligible. The results of this study enhance the understanding of this process.