Abstract: In this study,based on the monitoring of ambient volatile organic compounds (VOCs) in Ma'anshan City from September 5 to 15,2023,the characteristics of VOCs and source appointment were analyzed.The results showed that the average concentration of VOCs during the mid-term of O₃ pollution episode was 21.17×10^-9 in Ma'anshan City,which was 21.4% and 17.0% higher than that in the pre-pollution and post-pollution phases,respectively.The NO₂ average concentration was 18.5 μg/m³,which was 35.9% higher than the pre-pollution level.During the pollution period,elevated concentrations of O₃ precursors (VOCs and NO₂) combined with meteorological conditions such as high temperature (>30 ℃),low humidity (<60%),and light wind (<3 m/s),led to a 54.2% increase in O₃ concentration.Composition analysis revealed that alkane constituted the largest proportion of VOCs (33.6%),followed by oxygenated volatile organic compounds (OVOCs) and halogenated hydrocarbons,contributing 25.5% and 21.1%,respectively.Alkenes,aromatic hydrocarbons,and OVOCs had significant impacts on the generation of O₃,each contributing over 25%.The results of source apportionment showed that VOCs in the O₃ pollution episode mainly came from industrial sources (38.3%) and combustion sources (32.7%),and contributed significantly to ozone formation potential (over 20%).Therefore,the adjustment of industrial and combustion processes is important for the prevention and control of O₃ and its precursor pollution in Ma'anshan City.