SF6 gas mixture is one of the popular SF6 alternatives. For the purpose of quantitatively evaluating the arc extinguishing performance of SF6 mixtures,one-dimensional arc decaying model and Boltzmann equation are combined to divide the whole arc extinguishing process into thermal recovery stage,pre-dielectric recovery stage and post-dielectric recovery stage,which are evaluated by three parameters,namely thermal recovery rate,pre-dielectric recovery rate and post-dielectric recovery rate,respectively. The harmonic mean of the above three parameters is calculated as the harmonic average recovery rate to evaluate the arc extinguishing performance of SF6-N2,SF6-CO2,SF6-CF4 and SF6-Air mixtures. Based on the proposed method,the effects of SF6 proportion,buffer gas type and gas pressure on the interrupting performance of the SF6 mixtures are preliminarily investigated. The results show that the overall arc quenching ability of the gas mixtures presents a decreasing trend as the lowering of SF6 proportion. Among the four gas mixtures with SF6 proportion ranging from 10% to 50%,the SF6-N2 gas mixture has the best interrupting performance,followed by SF6-Air,SF6-CO2,and SF6-CF4 successively.