Abstract: In this paper,based on the concentration data of six air pollutants in the main urban area of Nanchong City,the air quality index,air quality index levels and the time series distribution of the primary pollutants from 2014 to 2020 were studied.The results indicated that with the prevention and control of air pollution,the concentration of air pollutants in Nanchong had gradually decreased,the number of days with primary pollutants decreased year by year and air quality gradually improved.Air quality showed significant seasonal differences due to pollutant rhythmicity,the air quality was worst in winter,followed by spring,relatively light in summer,and lightest in autumn.The seasonal distribution of the primary pollutant types was characterized by:the highest number of days with primary pollutants in winter,followed by spring and summer,and the lowest in autumn.Spring,autumn and winter were dominated by PM_2.5 pollution,while summer was dominated by O₃ pollution.From a year-round perspective,PM_2.5 had a prominent position relative to O₃.While continuing to control the total emissions of air pollutants,fine and cooperative control of fine particulate matter,nitrogen oxides,volatile organic compounds and sulfur dioxide might contribute to the prevention and control of air pollution at this stage.