In order to improve the arc-quenching capability of jet stream arc-quenching lightning protection gap, it is very important to understand the arc-quenching principle and the influence of the controlled length of airflow channel on the arc-quenching process. This paper analyzes the feasibility of the jet stream to extinguish the arc from the perspective of energy balance, and deduces that the velocity of the airflow is positively correlated with the controlled length of airflow channel, and that increasing the controlled length of airflow channel can promote the airflow development, enhance convective heat dissipation power, accelerate arc cooling, and thus improve the arc-quenching efficiency. A two-dimensional geometric model of the arc-quenching channel is built through COMSOL Multiphysics simulation platform, and simulation of the arc discharge heat transfer process under the coupling of airflow is carried out, the effectiveness of the arc-quenching device is verified. Then the variable of the controlled length of airflow channel is altered to obtain the corresponding simulation results for comparative analysis. Finally, the arc-quenching experiment is setup for verification. The results show that extending the controlled length of airflow channel can extinguish the arc and inhibit arc reignition more quickly and effectively, further optimize the arc-quenching performance of the jet stream arc-quenching lightning protection gap.