In this paper, a two-dimensional axisymmetric module of gas arc extinguishing was simulated using energy balance theories. We used simulation to study the energy distribution change during the gas arc-extinguishing process. We built a lightning impulse current experimental platform according to the IEC standard, and experiments verified the preliminary conclusions of the simulation. Comparison curves of the experimental data and simulation calculations were drawn in the range of 20 kV to 70 kV. Simulation and experimental results showed that the arc-extinguishing ability of long-gap gas arcs is negatively correlated with voltage level and positively correlated with distance. Furthermore, within the allowable range of conditions, increasing the length of the chamber rather than shortening it helps to extinguish the arc more effectively and quickly.