Abstract: In order to evaluate the air quality improvement during the Ozone Control Action in Chengdu City in summer 2017, on-line monitoring systems were used to monitor atmosphere volatile organic compounds (VOCs) in the ambient air of Chengdu City. The pollution characteristics of VOCs and ozone formation potential were compared and analyzed. In addition, the Positive Matrix Factorization (PMF) model was utilized to analyze the main sources of VOCs. The results indicated that the VOCs volume fraction was 31.85×10^-9 in August 2017, which decreased by 32% compared to the same period in 2016, especially the concentration of aromatic hydrocarbon and halogenated hydrocarbon declined dramatically. The daily change of VOCs shows a bimodal pattern, peaking at 09:00 and 23:00, respectively. Furthermore, the average hourly volume fraction of VOCs is lower than that of the same period of last year during the Ozone Control Action. The majority of VOCs' OFP sensitive species is alkenes, accounting for 48% of the total OFP of VOCs. The OFP of VOCs is 61.89×10^-9 in August 2017, falling down 44% compared to the same period in 2016. VOCs source analyses by PMF model showed that the emissions of fuel volatile, solvent evaporation, industrial sources and biomass burning declined, while the ratio of emissions of vehicle and natural resources increased in the summer of 2017. Overall, the ozone control action of Chengdu City in the summer of 2017 had a significant effect on the control of atmospheric VOCs emissions.