During the military parade period in 2015, air quality in Beijing was analyzed to investigate the impact of regional-scale air pollutant control strategies on Beijing. Ground-observed meteorological data, regulated air pollutant concentrations, and chemical compositions of PM_2.5 were analyzed. The results showed that the average wind speed of north wind, temperature, relatively humidity and ground-level atmospheric pressure during the military parade period were at the same level with the adjacent period, whereas, frequency of north wind was obviously higher. In general, atmospheric dispersion conditions during the military parade period was more favorable than the adjacent period. The average concentrations of SO₂, NO₂, O₃, PM₁₀and PM_2.5were 2.7, 24.2, 63.2, 27.2 and 19.5μg/m³, respectively, which decreased by 26.0%, 31.3%, 24.5%, 59.0% and 59.4% compared with the adjacent period, respectively. The decrease of PM_2.5 was the largest, indicating the combination effect of reduction of primate emission and precursor emission. OC concentration (6.1μg/m³) was the highest in PM_2.5 chemical composition, followed by NH₄⁺ (3.8μg/m³)、SO₄^2-(3.4μg/m³) and NO₃^- (2.5μg/m³). Notably, secondary OC accounted for 57.6% of total OC even with the implementation of emission reduction measures. The net effectiveness of the emission reduction measures was calculated through comparisons of concentrations of air pollutants under similar meteorological conditions. Through the implementation of emission reduction measures, concentrations of SO₂, O₃, NO₂, PM₁₀, and PM_2.5 decreased by 50.0%, 0.7%, 42.1%, 45.7% and 48.6%, respectively. In addition, the mechanisms of the different variations of O₃during the APEC period and the military parade period were discussed.