Abstract: For the purpose of reducing the peak concentration of pollutants and slowing down the occurrence and development of heavy air pollution, the key regions have gradually implemented emergency measures since 2013. To assess the effect of the '2+26' cities emergency measures more objectively and to verify the results of air quality models, we conducted a methodological study on emergency assessment based on the routine monitoring data. Through extending the Lorenz curve connotation, PM_2.5, PM₁₀, SO₂ and NO₂ were taken as the research objects and the conception of ratio of pollutant high cumulative concentration was suggested for reference of the assessment of the mitigation effect of emergency measures. The results showed that:The ratio of high cumulative concentration of PM_2.5, PM₁₀, SO₂ and NO₂ in the autumn and winter in 2016 and 2017 decreased compared to the same period in 2015, with a decrease between 0.43%-3.80%; taking 2015 as the base year, the ratio of PM_2.5, PM₁₀ with high cumulative concentration in the '2+26' cities in the autumn and winter in 2016 and 2017 decreased more than that of SO₂ and NO₂. The ratio of PM_2.5 with high cumulative concentration in the autumn and winter of 2016 and 2017 both decreased by 2.23% compared with the same period in 2015; compared with the same period in 2015, the ratio of PM₁₀ with high cumulative concentration in the autumn and winter of 2016 and 2017 decreased by 1.89% and 3.80%. The study suggested that the emergency measures have played a significant role in reducing the peak concentration of the pollutants, moreover, they had worked better in reducing particulate matter than gaseous pollutants such as SO₂ and NO₂.