Abstract: In response to the challenges faced by the arc extinguishing performance of vacuum circuit breakers under high current fitting conditions, the physical mechanism and performance optimization strategies were deeply studied. Through theoretical analysis and experimental research, the evolution characteristics of plasma, material degradation mechanism, and the influence of synchronicity deviation have been elucidated. A comprehensive optimization scheme based on contact structure optimization, material improvement, and intelligent monitoring has been proposed. The experimental results show that the optimized vacuum circuit breaker has a maximum arc energy of 156 kJ, a maximum contact temperature rise of 72 K, a three-phase synchronization error of 1.2 ms, and a vacuum degree maintained at 8.5×10^-4 Pa when subjected to a high current of 80 kA. All performance indicators are superior to the standard requirements.