As power systems continue to evolve toward higher voltages and larger capacities, the interrupting performance of compressed SF6 circuit breakers plays a critical role in ensuring grid stability. This study employs finite element arc simulation experiments to investigate the influence of cylinder structural parameters on the gas flow field and arc-quenching performance, with a particular focus on how increasing the cylinder size by 12.5% affects the pressure inside the compression cylinder and the flow rate at the nozzle during both no-load and arc simulation conditions. Simulation results indicate that the optimized structure achieves a 14.3% increase in peak pressure under no-load conditions, a 15.3% increase in pressure values at the current zero-crossing point during arc simulation, and a significant increase in flow rate at the nozzle. Additionally, it maintains a more sustained high-pressure gas flow and stronger arc-blowing effect. The study confirms that increasing the cylinder volume can effectively enhance the circuit breaker’s interrupting capability, providing a theoretical basis for high-voltage circuit breaker design and offering important engineering guidance for the development of next-generation high-capacity circuit breakers.